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. OPEN DESIGN: These drilling depth limit rings are open type design, which can be fine tuned to meet more clamping requirements. EXCELLENT METAL: These stop rings are made of excellent zinc alloy, and wear resistant, and has a long service life. MAIN PURPOSE: These stop rings are suitable for carbon steel bits, which are clamped to limit the drilling depth, convenient and practical. SPECIFICATIONS: Including 3pcs metal stop rings, 3 sizes of 6mm, 8mm and 10mm, and equipped with a hex wrench, easy to operate., Manufacturer: Uxsiya