[Material and quality]: The collet nut of the ER11 collet is made of 42 crMo, which is hard and durable. [Other options]: There are more types of nut hex for spindle motor to meet your needs. [Great Replacement]: The hex clamping nuts are a great replacement for the broken part. Most tool holders will fit. [Functions and Work]: Rod extension rod holder is used for ER tool handle, tool rod, drill bit for l extension rod nut, the drill bit and other tools. [Application and Usage]: This topdirect spindle motor is widely used in household and office equipment, communication equipment and other mechanical engineering companies."