This is a blue Pure-Tech Xtreme 4" Aluminum Block Strap. Xtreme Aluminum Block Straps feature Pure-Tech's industrial strength Velcro straps attached to aluminum mounting blocks that are designed to be securely mounted on wood or metal RC models. These straps can be used to secure batteries and electronics, and will keep your prized components solidly attached in even the roughest conditions. The 4" straps are recommended for smaller 1S to 4S LiPo flight batteries. Package includes one strap and four 4-40 x .42" button head screws.
NOTE: Length is 4", measured from aluminum block mounting hole to the opposite block mounting hole.