Material: Made of high quality carbon steel for good durability. The is blackened with anti-rust oil to improve the anti-rust performance. Safe and sturdy, the screw-type collar not damage the drill bit. Drill Stop Bit Collar Set: 8 stop collar sizes of 1/8 inch 1/4 inch 7/32 inch 1/4 inch 5/16 inch 3/8 inch 7/16 inch 1/2 inch for the most common drill sizes to suit your various DIY production work using needs. Suitable for twist drill bits or point drills or any type of bit. Precise and Efficient: Once the stop ring is fixed on the drill, it not shift. Helps you drill multiple holes quickly and easily to a consistent, precise depth. Solve the problem of your repeated deep drilling or drilling too deep. No more wrapping tape around your drill bits to control depth, save time and achieve greater accuracy. Easy to Use: Each stop ring has a locking screw that allows it to lock securely in any position on the drill bit, and the included hex wrench makes it easy to tighten and adjust quickly and easily, accurately control the depth of the hole you are drilling., Weight: 0.14991433816 pounds, Manufacturer: Prterver