The Manfrotto 046MC Expan Drive Set with Metal Chain allows
easy raising and lowering of rolls of background paper without lowering
the support stands. The system uses two expandable technopolymer inserts
to support a single roll of seamless paper. Tightening each side
expands the drive inserts from 1.8" to 3" to grip the roll solidly from
the inside. One side has a large toothed gear to which a metal link
chain affixes, permitting convenient raising and lowering of the
background paper roll. The other side has an adjustable tension drag.