I have a SWFA 3-15x 42mm scope. I went with the Vortex caps. The rear one is fine, but the front one doesn't quite fit right. It's too loose. I was having a problem with it sliding back under recoil. So I got an o-ring and that stopped the sliding, but created a new problem. Now it pulls off the end of the scope when I try to open it. I have the right size according to the website. The next size smaller would be too small. It's like my scope is in between sizes. Anyway, I am now looking for better lense caps. I don't want to spend hundreds of dollars on lens caps. I just want ones that fitnand function properly. Any suggestions?