I am new to the idea of optics on handguns. I got an optics ready slide for my G19, and was ready to get the Trijicon RMR everyone was recommending to me. I decided to buy a pre-owned RMR to save some money, especially in case my soon-to-be 54 year old eyes did not take to an optic sighted handgun. MisterK42 had a like new RMR cc with a 3.25 dot for sale. I contacted him and we arranged to meet. He asked what handgun I was going to mount it on, since he had a Sig 365 adapter available. I told him my host gun was a G19. He immediately told me he did not think it would fit. I contacted a buddy that works for Glock, and he confirmed the cc would not fit my G19 MOS slide. Mister42K was extremely understanding, and said no problem. This makes our transaction a successful non-sale. I hope Mister 42K has something I'm interested in at some point in the future. I would buy from him without hesitation. His understanding and insights are much appreciated!