Red dot sight with 7 brightness settings and off setting, elevation and windage adjustments, mounting mechanism suitable for any RIS rail, and flip up covers. Simple enough, it does it's job.
The highest brightness setting works perfectly in direct sunlight, and you can dial it down from there.
Sturdy construction of metal and rubber.
Easy to attach to a rail.
Easy to adjust, you just need a penny.
Comes with a battery already installed and an extra in the box.
Comes with a microfiber cleaning cloth.
The lack of clear protective covers might be an issue for some, I don't mind having to flip up the covers though.
THE BIGGEST PROBLEM: Although you won't have to remove the battery cover for quite a while (the battery lasts a long time and is preinstalled), it is extremely difficult to remove. There is no slot for a coin to insert in the top and unscrew. There's only some serrated edges on the side for traction, and those edges are about an eighth of an inch thick, so they just push into your fingers whenever you have to unscrew the battery cap. It's a terrible design, but nothing to inhibit the purpose of the item. You can screw it off after some force, but it's not pleasant.