I'll admit, I was operating on the belief that suppressor height sights allow the dot to absolute co-witness to the sights. That said, I also understand that there is probably no standard for iron sight height over bore. Hell, the set I put on this ZP upper is a supposed matched set and it shoots low consistently! They're AmeriGlo, which I thought was Glock OEM and a decent option, but perhaps I need to stick with Trijicons..