Adjustable Shower Door Rollers Shower Door Wheels, 8pcs Double Twin Top / Bottom Shower Door Rollers Runners Pulleys Wheels Bathroom Replacement Parts Replacement Twin Roller Shower Door Wheels Can I replace just a single roller at a time? Yes that's fine, as long as you're careful not to damage any of your other existing rollers then there is no reason to replace more than you need to. Premium Materials for Durability: Crafted with precision, our 23mm Sliding Shower Doors Wheels feature a copper swing and electroplated plastic alloy... Do I need upper or lower rollers? The upper rollers more often than not will have height adjustable wheels, either on a screw thread or nut and bolt. LumaGrove Shower Door Rollers 8pcs 23mm/25mm/27mm Shower These rollers are sold singularly The lower rollers will be spring loaded so you can lower the wheels and release the spring once they're in position in the track to lock them in place. 23mm/25mm Shower Door Rollers Zinc Alloy Double-Wheel Sliding Shower Door Roller Bearing Wheel Runners Replacement. 2 sold. US $8.66. 3% off US $8.93 How do I know which rollers I need? If you scroll down we have an easy to follow measurement guide. If you're struggling to find the correct one then feel free to reach out for help. Please check your measurements against the measurements that we show, if your measurements do not match then it's likely that you need a different roller.