Feature:1. Square drill bit cannot be used on electric drill , drill square holes to fit square drill bit (recessed and spigot machine) to use 2. Recessed hole and square spigot drilled through horrible outer sleeve in the middle of the combination 3. Reduce the labor intensity of construction workers, accelerate the pace of construction, reduce construction costs for the construction, installation, renovation, decorative industries 4. Excellent blade grinding process, edge is sharper and more durable 5. The standard groove is designed to facilitate chip removal and improve drilling efficiency . 1pc 16mm Square Hole DIY Drill Bit Cutter Specification:Descriptions: This square hole drill bit cannot be used on an electric drill , drill square holes to fit a square hole drill bit (recessed and spigot machine). The standard flute is to make it easier to remove wood chips and improve drilling designed efficiency. Excellent blade grinding process, the edge is sharper and more durable . Features: Square drill bit cannot be used on electric drill , drill square holes to fit square drill bit (recessed and spigot machine). Recessed and spigot square hole drilled through a terrible outer sleeve in the middle of the combination. Reduce the labor intensity of construction workers, accelerate the pace of construction, reduce construction costs for the construction, installation, renovation and decorative industries. Excellent blade grinding process, the edge is sharper and more durable . The standard groove is designed to make it easier to remove wood chips and improve drilling efficiency. Square drill bit is mainly used for woodworking. technical date: Material: high- speed steel Color : as the picture shows Size(Optional): 10mm/16mm Length: 203mm (10mm diameter); 208mm (16mm diameter) Weight: 166g The package includes: 1 x square hole drill bit . 1pc 16mm Square Hole DIY Drill Bit Cutter