High Quality Aluminum Alloy Material: Lightweight metal aluminum, strong hardness, wear resistance, high temperature resistance, this kind of drill stop has a long service life, better performance than plastic, strong fixity Firmly fixed: The drill bit limit ring set can accurately control the drilling depth without damaging the drill bit, with a nylon inner ring that is easy to lock and will not loosen, effectively avoiding wear and tear on the locking part of the drill bit. Making these drill depth limiting rings perfect for professionals and DIY enthusiasts to use in production or repetitive drilling projects Adjustable Inner Diameter: The inner diameter of the 2 installed drill depth stops can be adjusted to precisely apply drills of different sizes. Large for bit widths 15/64"-7/16" (0.23"-0.43"); Small for bit widths 5/64"-3/16" (0.078"-0.18") metal drill Precise limit: Quick adjustment, precise control of drilling depth, making drilling faster and more accurate, so that woodworking work more convenient Wide Range of Appli