Got one of these as an alternative to getting a full-on tac flashlight. I already had a cheap 1" flashlight, so I figured that this would work with it quite well. Thankfully, it did. The metal feels a bit cheap, but at a little under $10, you get what you pay for. It did come with everything you need to install it and the flashlight, however. The nut for the rail mount can be screwed off with your fingers, and it comes with (what looks to be) a 2.5mm hex key to unscrew the clamp. The offset also makes it easy to toggle your flashlight on and off, too, as I can still have most of my hand on the foregrip of my A&K Masada yet bring my thumb around to work the on/off button on the back of my light. Haven't had a problem with it yet, but at under $10, it's not like I will have wasted too much money if it breaks somehow.
-easy to take on and off
-comes with a 2.5mm hex key
-offset makes it easy to turn a flashlight on/off manually
Seriously, at under $10, how can you go wrong with this? Get it.