The threads on the tube end of these fittings are Class 3A or 3B and adhere to tighter tolerances than other 37° flared fittings.

Use these fittings at pressures up to 9,700 psi. Also known as instrumentation fittings, they are made to tight tolerances for use in high-precision applications. They are compatible with Swagelok®, Let-Lok, and Parker A-Lok fittings.

Also known as JIC (Joint Industrial Council) fittings, these provide a tight metal-to-metal seal on steel tubing that is flared to 37°.

These fittings have two sleeves for extra gripping power. They bite into steel tubing as you tighten the nut to form a strong seal.

No sleeve is required to assemble these fittings, which makes for a faster, more convenient installation compared to 37° flared fittings. They are also known as refrigeration and SAE fittings.