1. It is made of M35 high-speed steel full-grinding. It is vacuum heat-treated and is suitable for the opening of stainless steel plate aluminum alloy zinc and other thickness below 2MM. 2. The handle has an irregular handle shape to enhance the holding force. Note: 70mm and below specifications, the chuck with a handle of 10mm or more is available; 70mm and above, the chuck with a diameter of 13mm or more is available (metal open) Hole diameter size error range ¡À 15 wire length error ¡À 2mm) 3. Diameter ?14-?90mm, inner diameter of drill hole is about 15mm 4. Applicable equipment: hand drill, bench drill or other flat drill equipment, the clamping range can be used below 10MM-13MM.