Design details:3"pulley, by 2 pieces of 1.2mm thick Galvanized Steel riveted composite, inside 9 beads, outside 6 rivets evenly fixed inner ring, thickness:1.2mm clip:2.0mm. Single wheel weighing 100kg/220lbs,for Torsion Spring Doors up to 12 Feet Tall & Extension Spring Door to 9 Feet Tall.
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