Description:- Fits 20mm Picatinny rail.- Picatinny rail adaptor/riser.- Can be used to raise Picatinny rail.- Sometimes can be see through.- Length:143mm.- Weight: about 110g.- Height: 27mm.- Top Picatinny rail width: 20mm.- Bottom Picatinny rail width: 20mm- Material: aluminum alloy.Package Includes:- 1 x 20mm Picatinny (bottom) rail to 20mm Picatinny (top) extension rail adaptor/riser.