new Name: Square Hole Saw 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 . 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.