For sale is a B-J Tool Co. Type AT15-4-5/8-C8 Collet Type Holder. Made in the USA. The following dimensions were measured, to the best of my ability, using a 0.001" reading dial caliper: Overall length of holder 6.860" / Major diameter of external threads on holder 1.875" / Minor diameter of internal threading of holder 1.000" / Width of internal taper at nose of holder 1.565" / Hole in thread-on nose-piece of holder 1.112". NOTE: This B-J Tool Holder is a NEW, Unused and Never Installed item. Please feel free to ask any relevant questions regarding this listing.