Enclosed reflex on the RMR footprint, the same cut as a Holosun 407C or 507C. Black aluminum housing, and the LED sits behind glass so rain and lint stay off it. The reticle is a 2 MOA or 6 MOA dot with a 32 MOA circle, so you can pick the dot size and still have the ring when you want a faster index.

Clicks are 1 MOA. There are 8 day settings and 3 night settings, a 660 nm LED, an IPX7 rating, and it is parallax-free with unlimited eye relief. It bolts to an RMR-cut slide. A Glock MOS or other optics-ready gun still needs the RMR plate made for that gun. Set the lugs flush on the slide before you torque the screws.

Power is the part to understand before you buy it. There is no CR1632 to swap. The cell is internal and rechargeable, and you charge it with the magnetic cover in the box. Handy at the bench. Less handy if it dies at the range and the cover is in the other bag. Osight publishes a working range of 32–113°F. That covers a warm range day. It does not cover a holster or a truck in a Minnesota January. If you need the optic below freezing, choose one whose published range includes that cold.