Cage system paint roller frame,diameter of main rod 6mm,chrome-plated.5 wires,zinc-plated. W-516 38mm Cage roller frameSize: 7",9" (other sizes is available)Dia. of main rod: 6mm5 wires: dia. 3mmSurface treatment: main rod chrome-plated, 5 wires zinc-platedPlastic handle: PPType: Cage style (suitable for American style roller cover)