Offered here is a Sioux Valve Seat Grinder Stone Set

Included are 12 "General Purpose"  80 Grit Stones. The threads are 11/16

and will work with Sioux, KO Lee, Winona, and Thor.

The sizes are 1 1/8", 1 1/4", 1 3/8", 1 1/2", 1 5/8", 1 3/4", 1 7/8" , 2.00", 2 1/8", 2 1/4", 2 3/8", and 2 1/2"  

These stones can be dressed at any angle.