Thread-Locking Insert 1/4"-20 Inside, 3/8"-16 Outside

These inserts reduce at 3/8"-16 threaded hole to a 1/4"-20 threaded hole.
Use them to bolt two 1-2-3 blocks together. Use them to reduce the hole in 7/16" or 1/2" T-slot nuts to 1/4"-20 thread.
These inserts use Loctite® adhesive to keep them in place. The adhesive reaches full strength after 72 hours.
Set the insert with a bolt and two nuts, or use a slotted screwdriver.

These inserts can be used in 1-2-3 blocks so you can screw two 1-2-3 blocks together.

Use them to reduce the thread size of 7/16" and 1/2" T-slots when you need to use 1/4"-20 fasteners to hold things down to the mill table. 

Two uses that come to mind are mounting the 5602 or 5604 rotary tables and bolting down a 1-2-3 block as a work stop or square.