The WSHL is designed to work with the Simpson Strong-Tie® Quik Drive® auto-feed screw driving system. This screw is ideal for securely fastening subfloor panels to floor joists. The Quik Drive system features non-skid teeth that provide increased stability resulting in uniform toenailing and countersink on slick surfaces. WSHL Subfloor Screw (Collated) — #7 x 1-3/4 in. #2 Square Drive, Gray Phosphate (2000-Qty) (Pack of 100).