characteristic: Note: the width of the exposed clamping part is about 20mm, and the diameter of the exposed part is 38-43 mm. If your electric drill is not the size stated in the appeal, please take a picture carefully. Rechargeable (lithium battery series) electric drills are not suitable for this bracket. This product is suitable for old bench drills and household bench drills. Requirements: The maximum diameter of bearing circle clamp is 55mm. The height of the chuck is 10 cm. The square hole drill adapter is compatible with drill bits and hand drills, making it a multifunctional tool for various applications. Especially suitable for woodworking, furniture manufacturing and other related industries. The square hole drill for wood is easy to install and remove, so you can quickly install or remove yourself, saving time and effort. The square hole drill mounting bracket is made of materials castings and is durable. describe Name: square hole drill bracket set Material: Metal+Plastic colour: Black+Silver Package Contents: 1 x Square hole drill bracket set