BW&reg; DIY 0-14mm Steel Core Drill Bit Expanding Hole Opener Reamer tool for RC Model Airplane Car Propeller High quality steel with super hardness. Hole saw size adjustable: 0-14mm. Compact and portable design. Especially suitable for RC airplane car Slip-resistant designed handle and optimal shaped drill for comfortable grip and easy operation. Also ideal for electricians, plumbers and heating engineers, carpenters, etc.