I have bought a few and all have worked and held zero. That said they are all range guns, so they aren't tossed around or abused.
This one has worked well for a couple of my AR pistols. The other CVLife, and Brownell sights have worked equally well in my experience.
Edit: After a brief look on Amazon, the Fyland, Dagger Defense, and similar ones should all work just the same. They all roll off the same Chinese factory line.
Its like 26 bucks and would never last in irl combat https://www.amazon.com/CVLIFE-1X22X33-Green-Sight-Reflex/dp/B00A36MKUO
Hey I just bought one works amazing
CVLIFE 1X22X33 Red Green Dot Gun Sight Scope Reflex Sight with 20mm Rail https://www.amazon.com/dp/B00A36MKUO/ref=cm_sw_r_cp_api_glc_fabc_CHQQGCFY4H2P2KRJDSS3