I have a forward thumb grip on my S1 (Target II), S2 and CZ 75 Compact (SDP). All models have slide catches with the thumb grip built in. The S2 slide catch also fits the CZ 75 compact. The Czechmate has a thumb grip that attaches to the red dot platform. As an elderly shooter I find the thumb grips are a must for accuracy, especially for lighter pistols like the VP9, Sig P229 and M and P S and W.