YHM

The YHM BUIS is a basic unit that has a cost of roughly half that of many other BUIS. It is manually raised and lowered. It locks into position, and to retract the sight, you press down on the button, then fold it flat.

NOTE- In this picture, the side clamp of the YHM BUIS is not fully engaged into the side of the upper receiver. This is not an issue with the BUIS. I borrowed the BUIS for the pictures, and didn't tighten it down enough to lock it in position.