The peice itself.
The attachment as you buy it.
It was originally intended to be a guide to cut holes in drywall for electrical sockets or other needs. My Dad cut down the guide and used epoxy to fasten a peice of plex as a new guard/guide and the tool has to be cut down, so the cutoff wheel will stick out far enough to make it effective.
This can be used to trim your rails on bent blanks you make yourself or the ones that DPH arms is selling which are similar to the old ACE arms blanks.
Cutting rails in a 1911 project as well. A depth guide could be fitted on the tool as well. Remember if a depth guide was attached that the wheels do degrade as you cut and it will change your depth, but not a bad idea.
I'm sure some of the builders around here can thing of uses for this homemade tool as well.