This adapter converts a 1 1/4-inch UNC shank to SDS-plus. Made of 45 steel, sturdy and durable, and will not break easily. Suitable for all hammer drills with an SDS-plus shank. For use with core drills, UNC thread with an SDS-plus shank. Please check shank compatibility before purchasing. Attention! This is SDS-plus, not SDS-max!!! This adapter cannot be used in hammer mode.