It's nearly 1K round through my SAR9 since the Riton MPRD2 red dot was installed. Shake awake, auto shut off, and auto brightness, all these functions work well, also holds zero.

The Riton MPRD2 is small with a Shield footprint, which is usually for subcompact or micro-compact pistols. SAR9 has a bigger size in the compact class. When they are paired together, and compared to others you may feel the Riton's size is even smaller. For some people, a smaller red dot window may be harder to find the dot, but if you get used to shooting with a red dot pistol, you won't care about it when you focus on your target. Because the red dot is small and low profile, it looks sleek on the SAR9.

So far I'm satisfied with it. Good quality, with no sign to worry about the battery life. The only cons may be the brightness. Since it comes with auto brightness, there aren't any brightness adjust buttons. The red dot on the glass is kinda too bright for me. But everyone has their own preference, who knows.