Features: Brand new and high quality Strong metal material ensures maximum strength and durability for long lasting usage. The two-wire design provides greater retention and the drill bit can be locked securely without the top phenomenon of a single wire hole. It is used to fix the drill bit, limit the drilling depth of the drill bit,and ensure that the drilling depth of the drill bit is consistent. It is recommend to use drill stop collars with a lubricants to prevent burning of the material surfaces Greatly improve the accuracy, save-time and convenient for operation. Specifications: Material:Stainless Steel Type:6Pcs/8Pcs/12Pcs Package Includes: 3 Package Optional: Package 1 Include:6x Drill Bit Limit Ring 1x Wrench Package 2 Include:8x Drill Bit Limit Ring 1x Wrench Package 3 Include:12x Drill Bit Limit Ring 1x Wrench note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item.