Double side Clamp
Height 0.825 total and 0.45 between clamping surfaces ( between rails -picture 1)
One side open complitly to place rail into clamp from top. Other side has two V cut to prevent rail from falling out when jaws are not closed. That also required rail to be slid into clamp and not placing it into clamp from top/bottom. Small V on end also prevent any object to fall out if clamp is not closed or opened by accident. I strongly suggest using that side of clamp as bottom clamping surface.