None. It is cut for direct mounting optics with an RMSc footprint. The Holosun HS407K and HS507K are excellent options, but you will need to buy a couple 6-32X1/2 hex flat head cap screws to mount them to the M&P 22 Magnum, as unfortunately that size screw does not come in the box with the optic. I had to pay a whopping $0.37 each for mine.