The Kupo Background Paper Drive Set is a pair of adapters that expand and lock securely inside the core of a roll of seamless paper. The adapters can expand to accommodate paper core sizes from 46mm to 78mm in diameter. There is a drive side with a cog that accepts a metal chain that is driven by the metal chain to raise and lower the paper and a tension side with a knob that controls the amount of tension, preventing the paper from unrolling by itself due to gravity. The 13ft stainless steel metal chain will not break under tension and is kept taut by a chain weight that hangs from the bottom of the chain loop. Now with the addition of a metal chain, rolling up and down backgrounds is smoother than ever!