System of Measurement System of Measurement |
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Thread Size Thread Size | Show |
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Material Material |
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For Tap Thread Size For Tap Thread Size |
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Threaded Insert Type Threaded Insert Type |
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Key Locking | Helical |
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Thread Locking |
For Maximum Hole Diameter For Maximum Hole Diameter |
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Key-Locking Insert Wall Style Key-Locking Insert Wall Style |
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Thread Direction Thread Direction |
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For Use In For Use In |
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Thread Spacing Thread Spacing |
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Passivation Passivation |
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For Tap Type For Tap Type |
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End Type End Type |
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RoHS (Restriction of Hazardous Substances) RoHS (Restriction ofHazardous Substances) |
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External Locking Type External Locking Type |
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Tensile Strength Tensile Strength |
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REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration,Evaluation, Authorization and Restriction of Chemicals) |
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About Nuts, Materials, and Finishes
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How to Install Key-Locking Inserts
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How to Install Helical Inserts
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About Helical Insert Length
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Alloy Steel Socket Nuts

Also known as Allen nuts, use these with socket head cap screws in recessed holes and tight spaces that don't have enough clearance for a wrench. Tighten them with a 6-point hex key. They can also be used as an insert by pressing or drawing them into nonhardened steel, cast iron, or soft nonferrous metal or by molding them into plastic, ceramic, fiber, and similar materials. Made from alloy steel, they're comparable in strength to Grade 9 bolts.
For technical drawings and 3-D models, click on a part number.
Thread Size | OD | Ht. | Threading | Thread Dp. | For Hole Dia. | Hex Key Size | Each | |
Alloy Steel | ||||||||
---|---|---|---|---|---|---|---|---|
7/8"-9 | 1.36" | 1.34" | Partially Threaded | 0.7" | 1.418" | 7/8" | 000000000 | 000000 |
Black-Phosphate Steel Key-Locking Inserts

A black-phosphate finish provides mild corrosion resistance. Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. Use them to repair or change threads in soft metals such as aluminum. They’re comparable to Keensert® inserts. Installation requires a drill bit, a standard tap, an installation tool, and a hammer.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole with stripped threads.
Inserts with an extra thick wall are stronger than thick- and thin-wall inserts. Use them to reduce the size of tapped holes.
For technical drawings and 3-D models, click on a part number.
Inserts | ||||||||||
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Each | Installation Tools | |||||||||
Thread Size | For Tap Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | No. of Locking Keys | 1-9 | 10-Up | Each | ||
Black-Phosphate Steel with Thick Wall | ||||||||||
7/8"-9 | 1 1/4"-12 | 1 1/4" | 1 3/16" | 1 3/16" | 4 | 000000000 | 000000 | 000000 | 000000000 | 000000 |
Black-Phosphate Steel with Extra Thick Wall | ||||||||||
7/8"-9 | 1 3/8"-12 | 1 1/4" | 1 5/16" | 1 5/16" | 4 | 000000000 | 00000 | 00000 | 000000000 | 00000 |
18-8 Stainless Steel Key-Locking Inserts

Made of stainless steel, these inserts have good corrosion resistance. Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. Use them to repair or change threads in soft metals such as aluminum. Inserts may be mildly magnetic. They’re comparable to Keensert® inserts. Installation requires a drill bit, a standard tap, an installation tool, and a hammer.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole.
Inserts with an extra-thick wall are stronger than thick- and thin-wall inserts. Use them to reduce the size of tapped holes.
For technical drawings and 3-D models, click on a part number.
Inserts | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Each | Installation Tools | |||||||||
Thread Size | For Tap Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | No. of Locking Keys | 1-9 | 10-Up | Each | ||
18-8 Stainless Steel with Thick Wall | ||||||||||
7/8"-9 | 1 1/4"-12 | 1 1/4" | 1 3/16" | 1.188" | 4 | 000000000 | 000000 | 000000 | 000000000 | 000000 |
18-8 Stainless Steel with Extra Thick Wall | ||||||||||
7/8"-9 | 1 3/8"-12 | 1 1/4" | 1 5/16" | 1.313" | 4 | 000000000 | 000000 | 000000 | 000000000 | 00000 |
Mil. Spec. Stainless Steel Key-Locking Inserts

These inserts are made to stringent military specifications. Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. Use them to repair or change threads in soft metals such as aluminum. Inserts may be mildly magnetic. They’re comparable to Keensert® inserts. Installation requires a drill bit, a standard tap, an installation tool, and a hammer.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole.
For technical drawings and 3-D models, click on a part number.
Inserts | Installation Tools | |||||||||
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Thread Size | For Tap Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | No. of Locking Keys | Specifications Met | Each | Each | ||
303 Stainless Steel with Thick Wall | ||||||||||
7/8"-9 | 1 1/4"-12 | 1 1/4" | 1 3/16" | 1.192" | 4 | MS51831-110 | 000000000 | 000000 | 000000000 | 0000000 |
7/8"-9 | 1 3/8"-12 | 1 1/4" | 1 5/16" | 1.317" | 4 | MS51832-110 | 000000000 | 00000 | 000000000 | 00000 |
Mil. Spec. Alloy Steel Key-Locking Inserts

The strongest key-locking inserts we offer, these inserts are made to stringent military specifications. Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. Use them to repair or change threads in soft metals such as aluminum. Inserts may be mildly magnetic. They’re comparable to Keensert® inserts. Installation requires a drill bit, a standard tap, an installation tool, and a hammer.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole.
For technical drawings and 3-D models, click on a part number.
Screw-Locking Key-Locking Inserts

Forming the strongest hold of any of our threaded inserts, these inserts have a distorted internal thread to lock screws into place and keys that drive into surrounding material to prevent slipping and rotating. This creates a mechanical lock, which is stronger than the chemical lock from adhesive on thread-locking inserts. Because they’re made of a solid piece of metal, these inserts are also stronger than helical inserts, which are made of coiled wire. They're often used in molds, tools and dies, and suspension systems in vehicles to create completely new threads, add strong threads in soft metal, or replace existing threads that are damaged or need to be resized.
A dry-film lubricant makes it easy to install them and screw fasteners in. To install, use a tap to create the threads in your material and an installation tool to drive the keys into the material. All are made to tight tolerances with strictly controlled materials. Many inch sizes also meet military or aerospace standards for dimensions and material.
These inserts resist corrosion in wet environments. Inserts with thick walls are most commonly used; they’re stronger than thin-wall inserts and are used in larger holes.
For technical drawings and 3-D models, click on a part number.
Key-Locking Insert Assortments with Installation Tool

These assortments include various sizes of key-locking inserts with thick and thin walls, and an installation tool. Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. Use them to repair or convert threads in soft metals such as aluminum. They’re comparable to Keensert® inserts.
18-8 stainless steel inserts are more corrosion resistant than black-phosphate steel. They may be mildly magnetic.
Black-phosphate steel inserts are mildly corrosion resistant.
Choose assortments with thick-wall inserts for greater strength than thin-wall inserts, or to fill a large hole.
For technical drawings and 3-D models, click on a part number.
For Tap | ||||||
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Includes | No. of Inserts Included | Thread Size | Drill Bit Size | For Max. Hole Dia. | Each | |
Inch | ||||||
18-8 Stainless Steel with Thick Wall | ||||||
1/4"-20 Thread × 3/8" Installed Lg. (20 Each) 5/16"-18 Thread × 0.438" Installed Lg. (15 Each) 3/8"-16 Thread × 1/2" Installed Lg. (10 Each) 7/16"-14 Thread × 5/8" Installed Lg. (10 Each) 1/2"-13 Thread × 5/8" Installed Lg. (6 Each) 9/16"-12 Thread × 0.813" Installed Lg. (5 Each) 5/8"-11 Thread × 7/8" Installed Lg. (3 Each) 3/4"-10 Thread × 1 1/8" Installed Lg. (3 Each) 7/8"-9 Thread × 1 1/4" Installed Lg. (3 Each) 1"-8 Thread × 1 3/8" Installed Lg. (2 Each) Installation Tool | 77 | 7/16"-14 1/2"-13 9/16"-12 5/8"-11 3/4"-16 7/8"-14 1 1/8"-12 1 1/4"-12 1 3/8"-12 | X 29/64" 33/64" 37/64" 45/64" 53/64" 1 1/16" 1 3/16" 1 5/16" | 0.397" 29/64" 33/64" 37/64" 45/64" 53/64" 1 1/16" 1 3/16" 1 5/16" | 000000000 | 0000000 |
Black-Phosphate Steel with Thick Wall | ||||||
1/4"-20 Thread × 3/8" Installed Lg. (20 Each) 5/16"-18 Thread × 0.438" Installed Lg. (15 Each) 3/8"-16 Thread × 1/2" Installed Lg. (10 Each) 7/16"-14 Thread × 5/8" Installed Lg. (10 Each) 1/2"-13 Thread × 5/8" Installed Lg. (6 Each) 9/16"-12 Thread × 0.813" Installed Lg. (5 Each) 5/8"-11 Thread × 7/8" Installed Lg. (3 Each) 3/4"-10 Thread × 1 1/8" Installed Lg. (3 Each) 7/8"-9 Thread × 1 1/4" Installed Lg. (3 Each) 1"-8 Thread × 1 3/8" Installed Lg. (2 Each) Installation Tool | 77 | 7/16"-14 1/2"-13 9/16"-12 5/8"-11 3/4"-16 7/8"-14 1 1/8"-12 1 1/4"-12 1 3/8"-12 | X 29/64" 33/64" 37/64" 45/64" 53/64" 1 1/16" 1 3/16" 1 5/16" | 0.397" 29/64" 33/64" 37/64" 45/64" 53/64" 1 1/16" 1 3/16" 1 5/16" | 000000000 | 000000 |
Key-Locking Inserts with Installation Tool

Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. These inserts are used to repair or convert threads in soft metals such as aluminum. They’re comparable to Keensert® inserts.
18-8 stainless steel inserts are more corrosion resistant than black-phosphate steel. They may be mildly magnetic.
Black-phosphate steel inserts are mildly corrosion resistant.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole.
For technical drawings and 3-D models, click on a part number.
Stainless Steel Helical Inserts

Also known as Heli-Coil inserts, these inserts have coils that expand once installed to securely anchor the insert. All have a prong for ease of installation. An installation tool grips the prong and reduces the coil diameter, enabling the insert to fit in tapped holes. Remove the prong to insert the screw. Installation requires a drill bit, a helical insert tap, an installation tool, and a prong break-off tool.
For technical drawings and 3-D models, click on a part number.
Inserts | Through-Hole Taps | Closed-End Hole Taps | Installation Tools | ||||||||||
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Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | Specifications Met | Pkg. Qty. | Pkg. | Each | Each | Each | ||||
18-8 Stainless Steel—Right-Hand Threaded | |||||||||||||
7/8"-9 | 7/8" | 29/32" | 29/32" | MS122-89 | 1 | 000000000 | 00000 | 000000000 | 0000000 | 000000000 | 0000000 | 000000000 | 000000 |
7/8"-9 | 1.312" | 29/32" | 29/32" | MS122-129 | 1 | 000000000 | 0000 | 000000000 | 000000 | 000000000 | 000000 | 000000000 | 00000 |
Stainless Steel Screw-Locking Helical Inserts

A distorted thread grips the screw to resist loosening. Also known as Heli-Coil inserts, these inserts have coils that expand once installed to securely anchor the insert. All have a prong for ease of installation. An installation tool grips the prong and reduces the coil diameter, enabling the insert to fit in tapped holes. Remove the prong to insert the screw. Installation requires a drill bit, a helical insert tap, an installation tool, and a prong break-off tool.
For technical drawings and 3-D models, click on a part number.
Helical Inserts with Installation Tools

Inserts come with a through-hole tap and installation tool. Also known as Heli-Coil inserts, they have coils that expand once installed to securely anchor the insert. All have a prong for ease of installation. An installation tool grips the prong and reduces the coil diameter, enabling the insert to fit in tapped holes. Remove the prong to insert the screw.
Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | No. of Inserts Included | Includes | Each | |
18-8 Stainless Steel—Right-Hand Threaded | |||||||
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7/8"-9 | 1.312" | 29/32" | 29/32" | 6 | Drill Bit, Through-Hole Tap, Installation Tool | 000000000 | 0000000 |
Black-Phosphate Steel Easy-to-Install Thread-Locking Inserts
A black-phosphate finish provides mild corrosion resistance. Also known as E-Z Lok, these inserts use Loctite® adhesive to keep them in place. The adhesive reaches full strength after 72 hours. Installation requires a drill bit and a standard tap. Then set the insert with a bolt and two nuts, or use an installation bit.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole.
To drive slotted inserts, you can use a slotted screwdriver instead of using an installation bit or a bolt and two nuts.
For technical drawings and 3-D models, click on a part number.