Feature: Made of high quality chrome vanadium steel, blackened polished. Extend your router bits an additional 2-1/4" to provide the full depth of cut. Eliminate the dangerous temptation of withdrawing the shank from the collet. Suitable for woodworking trimming, milling, engraving machine. Specifications: Meterial: high quality chrome vanadium steel 1/2- Inch : Shank diameter: 1/2" (12.7mm) Hole diameter: 1/2" (12.7mm) Overall Length: 87mm Unit Weight: 136.2g 1/4-Inch: Shank diameter: 1/4" (6.35mm) Hole diameter: 1/4"(6.35mm) Overall Length: 88mm Unit Weight: 85g 8mm: Shank diameter: 8mm Hole diameter: 8mm Overall Length: 87mm Unit Weight: 86.3g Package Included: 3pcs Router Bits Collet Extension Note: 1. Please allow 1-3mm differs due to manual measurement. 2. Due to the different display and different light, the picture may not reflect the actual color of the item. Thanks for your understanding.