Black-Oxide Steel—Typically chosen for their appearance, these screws have a dark, matte coating for a finished look. They offer minimal corrosion resistance, so they're best for dry environments.

Zinc-Plated Steel—A common choice for areas with occasional exposure to moisture.

Black-Zinc-Plated Steel—The dark finish withstands occasional exposure to moisture while creating a finished look.

Tri-Lobe—The tri-lobular shank forms threads in thermoplastics such as polypropylene and ABS. These screws displace material to create a tight fit that resists vibration and prevents backing out. Because the shank isn't round, the diameter will vary slightly depending on where you measure it. They're comparable to Plastite screws.

Round—The sharply angled threads drive into plastic with less force and a lower risk of cracking than other tapping screws. The base of the threads is recessed to bite deep into material and hold tight. You can reuse these screws a few times without stripping the threads. They're comparable to PT screws.