#6 x 1-5/8" Coarse Thread Drywall Screw - Black Phosphate Box of 1000 screws For fastening drywall (gypsum board) to wood studs. Also used to attach wood fixtures. A good multi-purpose screw. Phosphate coating is used to reduce friction during installation and increase corrosion protection. https://www.adkausa.com/store/6-x-1-5-8-Coarse-Thread-Drywall-Screw-Black-Phosphate-Box-of-1000-screws-p688956411