I marked "Tall Sights" for the FNH 510 holster, but that is only because all FNH 510 MRD pistols have tall sights to co-witness with an optic. I suspect that those sights are already factored into your holster design, but I checked the box just to be sure. It is just a standard FNH 510 MRD with a Holosun red dot mounted to it.