This IFF Curtain Carriage is part of the IFF Top Rail System which suspends lighting and other accessories from the ceiling on a system of rails and moveable hangers, thus freeing up floor space. The steel FF3720C Curtain Carriage with ball bearings has a load capacity of 44 lbs (20 kg) and can support curtains up to 29.5' (9 m) in height. The recommended distance between carriages for ideal curtain support: 9.8-11.8" (25-30 cm).