Specification: Securely holds 1/4 – 5/8 square diameter tool bits Interchangeable with Dorian, Aloris, & Phase II BXA series tool posts. For use with BXA tool posts 250-200 or 250-222. Precision ground and hardened. Feature: The Product Has Passed Strict Quality Testing Durable And Easy To Install And Replace Cost-effective, Good After-sales Service.