I ordered this item last week and I just heard the knock on the door from the UPS man and there it was! I opened it it up and cleaned it (not that it was dirty, but I have OCD...so it makes me feel better to clean EVERYTHING that goes on my firearms) right away and mounted it on my new Smith and Wesson M&P 9mm. I thought this laser sight was going to be bulky and some-what large (regardless of the image on the OpticsPlanet website), but this thing is VERY SMALL! Which for me is a big plus. It mounted with no problems and I was able to change the beam with no problems either. I love the fact one can switch from a steady beem to a flashing beam. However, to change from one setting to the other, you need to remove the battery cover and turn a screw...which is not a problem. And what is very neat about this item once more is the fact that you can mount something else underneath it because it comes with a built-in mount just like the pictures show. :) Overall, I am VERY pleased with this product. It was worth every penny I spent and I am more then willing to buy a new one; maybe the green laser, I'm kind of tired of red...