Midwest Industries MK2 1913 Riser

This is a riser in the literal sense: a Picatinny rail on top, a Picatinny clamp on the bottom, and 0.625 inch of aluminum in between. It does not accept an optic footprint. It raises whatever mount you already own, which is the right tool when your dot is already on a mount you like and you simply want it higher.

Midwest sells it in 5, 9, and 13 slot lengths. The longer versions are the point: a 13 slot riser puts a red dot and a flip-to-side magnifier on the same continuous plane at the same raised height, which is otherwise fiddly to achieve with two separately-mounted risers that may not index identically.

The clamps are 4140 steel rather than aluminum, which matters on a riser because it carries the load of the optic plus its mount and sees more leverage than a mount clamped directly to the receiver. At 4.9 ounces for the 13 slot it is not light, and stacking a riser under a mount always adds more height variance than a single purpose-built mount at the height you wanted.