This is a Magpul Industries Accessory known as the XT Rail Texture Panel, model MAG012-BLK.
XT Rail Panels offer low-profile 1913 Picatinny rail coverage. The semi-rubbery material offers improved weapon control and rail protection. Easily cut for custom lengths" sections can mount next to each other to form a visually continuous cover. Each panel fits one side of a carbine-length rail. One panel per package.
Features:
Low-profile 1913 picatinny rail coverage
Semi-rubbery material
Easily cut for custom lengths
Improves weapon control and rail protection
