1. SCREW LOCKING: The drill stop ring is locked with screw, the clamping torsion is up to 4.5kg to prevent the plate from being punctured. 2. OPEN DESIGN: These drilling depth limit rings are open type design, which can be fine tuned to meet more clamping requirements. 3. EXCELLENT METAL: These stop rings are made of excellent zinc alloy, and wear , and has a long service life. 4. MAIN PURPOSE: These stop rings are suitable for carbon steel bits, which are clamped to limit the drilling depth, convenient and practical. 5. SPECIFICATIONS: Including 3pcs metal stop rings, 3 sizes of 6mm, 8mm and 10mm, and equipped with a hex wrench, easy to operate. Specification: Item Type: Drill Bit Stop Ring Material: Zinc Alloy Color: Silver Use: Applicable to carbon steel drill bits, which can be safely locked at any position along the drill bit Package Contents: 1 set of Drill Stopper Collar Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.