Description Special Reminding - These flute countersink drill bit set are machined from high speed steels and are available in 6 different diameter sizes. Size - 6mm(1/4), 8mm(5/16), 9mm(3/8), 12mm(1/2), 16mm(5/8), 19mm(3/4) Eliminates Chatter and Vibration - All have a 90 angle on the point for sharp and precise countersinking. The cutting edge is hardened and honed for sharpness. A Chatter-Free,five-flute designed with staggered cutting teeth aranged to insure free chip flow and rapid chatter free cutting. Mutiple Application - Ideal for wooden planks,fiberboard,particle board,plywood,plastic,alumiumn board ,pcb board and more Premium Design - Great for Sinking 90 Degree Holes into Wood and Soft Metals Countersunk Screws and Fixings.Suitable for DIY, Home and General Building/Engineering Using. NOTE:There will be a slight color difference between the picture and the actual product. Sweet Tips - 1/4 hex shank countersinks are fine for a quick drill. They dont slip in drill chucks. You can make deep countersinks easily by setting the countersinks depth stop to allow the countersink to drill more deeply into the worksurface. Be sure to measure the size of your plug to be sure your countersinks body will make the right-size hole.