Amazon.com: Letool 4pcs U type groove pulley nylon Guide Pulley Rolling Bearing U Groove Roller Wheel 8x40x20mm for Driving Mechanical Equipment, or Used in Doors and Windows : Industrial & Scientific
1pcs U groove / V groove steel wheel wire rope crossing roller 10/12*58*18mm 6201 bearing guide wheel|Door Rollers| - AliExpress
U Groove Guide Rollers (Double Bearings) (GRL-S2-R) | IMAO CORPORATION | MISUMI Malaysia