Specifications: Made of high quality material, durable and sturdy. Includes limit rings and L shape wrench. Mainly for fixing the drill bit, limited the depth of drill holes, make depth of the hole consistent. Item Name: Drill Stop Ring Material: Carbon Steel Quantity: 1 Set Features: Durable, Easy to Use, Portable, Useful M3: Inner Dia.: 3.2mm/0.12", Outer Dia.: 9.8mm/0.38", Thickness: 3.5mm/0.13", Height: 8mm/0.32" (Approx.) M4: Inner Dia.: 4.2mm/0.16", Outer Dia.: 9.8mm/0.38", Thickness: 3mm/0.11", Height: 8mm/0.32" (Approx.) M5: Inner Dia.: 5.2mm/0.2", Outer Dia.: 11.8mm/0.46", Thickness: 3.4mm/0.13", Height: 8mm/0.32" (Approx.) M6: Inner Dia.: 6.2mm/0.24", Outer Dia.: 11.8mm/0.46", Thickness: 3mm/0.11", Height: 8mm/0.32" (Approx.) M8: Inner Dia.: 8.3mm/0.32", Outer Dia.: 16mm/0.63", Thickness: 3.9mm/0.15", Height: 8mm/0.32" (Approx.) M10: Inner Dia.: 10.3mm/0.41", Outer Dia.: 18mm/0.71", Thickness: 3.8mm/0.14", Height: 8mm/0.32" (Approx.) M12: Inner Dia.: 12.2mm/0.48", Outer Dia.: 20mm/0.79", Thickness: 3.9mm/0.15", Height: 8mm/0.32" (Approx.) M16: Inner Dia.: 16.2mm/0.64", Outer Dia.: 24mm/0.94", Thickness: 4mm/0.15", Height: 8mm/0.32" (Approx.) Notes: Due to the light and screen setting difference, the items color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 8 x Drill Stop Ring (Different Size) 1 x L-shape Wrench