A rail-attach type 25mm flash light mount ring; designed to attached to a right side rail to position a flash light below and to the right.
The advantage of an off-angle flashlight mount of this design is that it occupies a side rail and not the bottom (left clear for lasers, grips, launchers, etc.) and yet places the light source more central to the bore axis than a side mounted flash light.
TSC makes this model in different colors and also makes the attachment bracket available without the 25mm ring.