Materials: brass, nylon outer wheel and stainless steel screw. High quality multi-functional small rollers. There is replacement shower door roller which will fix for you any sliding system in your home. Wheel Dimensions: 22.5mm(diameter), 7mm(thickness) Shower door rollers are internally threaded. Shower Door Runners for showers massage cabins, bathtubs, whirlpool and even for furniture fittings.