The grip on the X100F felt awkward for me, like it would slip from my hand. I tried a Gariz 1/2 case which was an improvement but still didn't feel right. I received my Lensmate thumb rest a couple of days ago. Works perfectly for me. It feels like a natural extension of the camera. I don't think about it being there, It just feels right. I did try the Gariz case with the thumb rest and the combination did NOT feel right. The thumb rest felt better with just the camera.