7 piece drill bit collars with depth stop rings that minimize deviation during operation. Compatible with 312 mm drill bits for wood, metal, and other materials For workshop projects, construction sites, or home repairs where consistent hole depth and alignment are critical, including cabinetry, plumbing fixtures, or automotive parts Ideal for professional woodworkers, metal fabricators, and enthusiasts who require millimeterlevel precision in drilling Crafted from hardened aluminum alloy bodies and 304 stainless steel set screws, this versatile set offers corrosion resistance and quickadjust functionality for effortless installation Use scenarios: Cabinetry installation or furniture fabrication requiring uniform hole depth Plumbing fixture mounting or automotive parts assembly where precise depth is essential General workshop tasks at construction sites or home repairs needing repeatable drilling depth and alignment