Recently picked up an Olight C for my Glock. I mounted it to my Glock 45 , Glock 49 and Glock 20. This window is BIG! I knew it was larger than Holosun but GD this thing is massive. It just looked so out of place on my Glock 9s so I decided to install on my Glock 20 and it fit perfectly! Going forward I'm probably just going to stick to Holosun unless I end up just really enjoying this site. But I'm leaning more towards the 407 or 507c as they are excellent carry options and perfect size for conceal carry. I'll update once I have a significant amount of rounds through it specially on a 10mm and let you know my thoughts.