DWC Series - #6 drywall screw, coarse, sharp point, bugle head, gray phosphate finish. DWF Series - #6 drywall to steel (33, 27, 18 mils / 20,22,25 gauge), fine thread, sharp point, bugle head, gray phosphate finish. DWFSD Series - #6 drywall to steel (54, 43 mils / 16, 18 gauge), fine thread, #2 drill point, bugle head, yellow zinc coating