When I received the Reflex Sightv, the battery contact was deformed and not making good contact with the battery. I suspect I am the the first owner of this device. After spending several minutes trying to see the red dot, I found I had to push the on/off/brightness knob sideways before rotating it to turn it on. If the device is on and the knob is jiggled side to side slightly it will turn off. If the device is rigidly mounted and pointed at a star, the red dot will shift off of the star when you move your head side to side or up and down. Some devises have parallax adjustment or parallax compensation to eliminate this problem, this device does not. If you want a cheap red dot sight to use on a low magnification telescope, this might be worth the price, providing the issue with the knob doesn't get worse.