I have them for my 637 and my dad's M-60, I sorta want them to be twins.
For a while I had them on my 638 to try and I kinda like them. Just SLIGHTLY more room for my pinky but still easy to hide. A little more if it is in a pocket but my plan is to have another one with boot grips if a pocket is the plan. I posted some pictures, not sure what thread now but you might find it if you search my posts.