The HD-801 Fitting Guide is made with file-resistant buttons having a radius of .242" for use when installing a Harrison Design grip safety. Also included is a smaller diameter spacer that is installed between the frame tangs to keep you from squeezing the tangs together if you tighten the screw too much. Be aware that while the guide buttons are "file-resistant", you can still damage the surfaces if you grind against them, or otherwise abuse them. Also be aware that the screw is very hard to source, so good practice is to keep the Fitting Guide assembled when not in use.
