Even though this didn't work for me, I gave it a 3 because if it will mount for you, then it's a good value. I couldn't mount this on my weaver rails because the front battery compartment hit my rail. I'm guessing that some rails must be different, because I find it hard to believe that they designed it to fit nothing. It's a shame too because the dot is actually really nice, especially for the price and the reticle is pretty clear and the unit is as light as $200+ units (though it's plastic). The other downside is that the zeroing adjustments are not protected, so you could mess them up putting the gun back in it's case or inadvertently hitting them.