Hook and loop fasteners consist of two distinct pieces. The rough, scratchy side is the hook because it is covered with several tiny hooks per square inch. Likewise, the soft, fuzzy side is the loop because it is covered with many small loops. The hooks engage the loops when the two sides are pressed together. This creates a bond that is exceptionally strong and allows for repeated use that lasts for thousands of cycles. http://www.quwinvelcro.com/hook-and-loop/adhesive-hook-and-loop/