Laminated loop fabric and sewed a strip of that VELCRO fasteners stuff along one edge so it sticks to the VELTEX fabric. You can put a lot of wires inside and close it up, tightly or loosely, as you choose. You can access wires anywhere you wish along the length. And since it comes with separate little mounting squares of double-sided tape on one side. WM11 is made of 100% nylon fabric with a thick polyester foam core that gives it good body and heft.