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" up to a maximum of 6-7/8". 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" up to 6-7/8". Thread size of 5/8" x 18. Hole Enlargement capable with hole saws with 5/8" x 18 threads. These adapters are only for use with the Milwaukee QUIK-LOK Hole Saw Arbor System