The Milwaukee 2 Pack of Reusable Quik-Lok Arbor Large Thread Pin Adapters are intended to be used with hole saws from 1-1/4 in. up to a maximum of 6-7/8 in. The Pin Adapter design prevents thread stripping and binding when using large diameter hole saws or encountering high torque. The threaded design is a universal fit compatible with all industry standard threaded hole saws from 1-1/4 in. up to 6-7/8 in. Thread size of 5/8 in. x 18. Hole enlargement capable with hole saws with 5/8 in. x 18 threads. These adapters are only for use with the Milwaukee Quik-Lok Hole Saw Arbor System.