#8 trim screws use bit T-10; #9 trim screws use bit T-15 Self-tapping, TRIM head screws; W-Cut thread design One pail contains 348 screws Climatek coated for all weather corrosion protection conforms with ICC#2442 TRIM head screw for any fine woodwork or carpentry application GRK TRIM Head Screws have the smallest screw head available and work great for most fine carpentry applications. Most material splitting is prevented because of the TRIM Head screw's exceptionally small head and the W-Cut thread design. The RT screws include a reverse threading under the head of the fastener. GRK has found that the reverse thread helps the screw head disappear beneath the surface of the classic wood composite material, reducing or eliminating the dimple that sometimes appears.