Kupo Background paper drive set is a pair of adapters that expand and lock securely inside the core of roll of seamless paper. One adapter has a plastic cog that accepts a plastic drive chain so that you can adjust the length of your background comfortably and a tension control so the background doesn’t unroll by itself due to gravity. The flexibility of this adapter can fit to 46mm - 78mm dia. tube size. ( The plastic chain and chain weight are included)