I bought a Packmyr (sp?) slip on for my 100 today, and it fits great. It was made for several model Glocks. A guy at the gun shop put mine on for me, and he trimmed about a 16th of an inch off the back side of it to make it fit perfectly. I like it so far, seems to be a big improvement. I'll let y'all know how I like it over time. For $10 it was worth a shot!