These Simpston Strong-Tie® screws are designed for fastening subfloor sheathing using the Quick Drive auto-feed screw driving system. Redesigned tip and thread patterns provide easy starts and up to 25% less torque while driving and 20 % faster driving. Less installation torque also means less wear on tools. The deep six-lobe recessed ribbed head provides clean countersinking and more secure bit retention for fewer cam-outs. The holding power of WSV screws reduces the gaps between the joist and subfloor that cause the floor to squeak. They also allow for easy back out for future access to floor cavities. 6-lobe T-25 drive bit, (replacement bit BIX25). Sold here in a box of 2000 nails.