... the roller tube running and drive the fabric remove up and down. Chain roller blinds could build in spring help system to ... of circumstance, non-deforming, exquisite appearance etc. Roller Blinds System Clutch: 38mm Aluminum Tube Fabric: ( 1%,3%,5%,10% 15% Openness in ... . Helper Spring System When the chain roller blinds is wide and high or the fabric is massive relatively, the spring help system ...