new Name: Square Material: steel Color: Silver & black 2 sizes : 10mm/16mm Length: 203mm(10mm diameter); 208mm(16mm diameter) Square hole drill can not be used on an electric drill, drill square holes need to fit a square hole drill drilling (mortise and tenon machine) to use. Mortise and tenon square hole drilled by the terrible + outer sleeve in the middle of the combination. Reduce labor intensity of construction workers, the construction speed, reduce construction costs for construction, installation, renovation, decoration industries. Arc design, exquisite sharpen durable. Use matters: Square hole drill is mainly used for woodworking aspects. Package included: 2 x Square Hole Drill Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.