GRK 61737 R4 PHEINOX 305SS ProPak #10 by 3-1/8-Inch Self-Countersinking Screws, (70 per Pack) GRK R4 Stainless Steel self-countersinking screw has a new under head with saw-blade like cutting teeth and six self-contained cutting pockets. Together they act similar to a circular saw-blade, transporting the drill dust away from the edge of the screw hole while cutting a perfectly clean hole into even the most brittle materials without cracking any surface treatment. This design also further enhances the R4's versatility by allowing the fastener to be installed without countersinking into even the hardest woods. The screw head closes the hole off with precision, leaving no damaged fibers around the head. Features Uses GRK T25 bit Self-tapping Self-tapping countersink head W-cut thread design PHEINOX 305 Stainless Steel USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.