Description: 1. Nylon belt roller with flat belt bearing and sturdy bearing design avoids sinking. Low noise, low vibration, high precision. Stable performance and durable. 3. High sealing performance, high operating performance. 4. Widely used in gearbox, instrumentation, electrical appliances, household appliances, combustion engines, transport vehicles, agricultural machinery, construction machinery engineering machinery, roller skates, yo-yo etc. Features: Product Name: bearing roller color: white; Size: 30 x 13mm (OD x T); U groove width: 6mm; Thread size: M6; Package contents: 4 x bearing pulley.