PRODUCT DETAILS Click an item to expand and learn more Overview BT 40 High Precision ER tool holders are mainly used for CNC milling machines. Made from alloy steel hardened to 54 - 56rc Tool holders balanced to G2.5 at 25,000 RPMs Coolant-through capability Concentricity is less than .0002 at collet face Rear thread for pull stud is 5/8-11 Spring collet not included Reviews ReviewsQ&ATrusted reviews byWe're looking for stars!Hear what other people just like you have to say about our tools.Read Our Reviews Questions and Answers Questions & AnswersHave a question?Be the first to ask something about this product.Ask a question