The Slide, from Elevated Technologies Inc., is an optic mount that has a height adjustment feature that allows you to create the co-witness of your choice. If you want to use lower sights and place your optic closer to the bore, you can do that. If you want to raise your optic out of the way of fixed iron sights, you can do that too.
Elevated Technologies Inc currently supports the Trijicon MRO and optics with the Aimpoint Micro hole pattern. Their modular two piece, dovetailed design seems like it could be made to support a wide variety of optics easily.
Check out ElevatedTech.com.