The 1401 Small Wheel Attachment uses a 1" wide belt.  Wheels sizes from 9/16, 3/4, 1", 1-1/2" can be used with this attachment.  

The 1401 comes standard with the AK2311 wheel which is 1" x 1"

Internal Grinding Attachments Convert Models 482, 760 and 1272 Grinders for Internal Grinding.

A variety of interchangeable wheel sizes are available to allow tight radius and internal grinding.