allows for faster hitting up close, and allows a way to zero the .22 unit carefully, if its POI is quite a bit different from that of the chosen 223 ammo. For really precise shots, you need the scope anyway. Leave the v notch ready for use, for fast work with the 223 (ie, 10" circles to 100m) and zero the other wing of the peep for 175-200 yds. Zero the scope for 300 yds, cause 150 yds stuff, you can handle with the irons. The v notch is of course zeroed at 50 yds with subsonic .22lr ammo, cause that's what's carried, for use with the 223 suppressor.