This is similar to other red dot sights, lights, and lasers that are made in China. They are inexpensive, fun to take to the range, use for plinking around, or using for airsoft or paintball, but I would not rely on it for self defense or where my life depended on it. This particular item is a laser/light combo that is similar in size and function to Streamlight TLR-2. You use the small 3-way switch on top to choose between laser, light, or both and then the rotary switch on the bottom allows you to choose between momentary-on or constant-on. The light is very bright at 800 lumens and lights your area well. The laser is bright and easily adjustable. It has held zero so far, but I have not tested for any significant period of time or on any caliber other than .22. It mounts to a variety of rails & weapons using the included adapters. This 4 star rating assumes that it will hold zero for an extended length of time on a variety of calibers higher than .22. (If it doesn't, I will update this rating accordingly). Overall this product works well and is a good addition to your firearm, but again, I wouldn't place it on a weapon where my life depended on it.