They're plastic sealed ball bearings, which offer smooth rotation, great accuracy of accessory as well as simplified maintenance.
• 950 Sealed Flanged Ball Bearings x2
• Applications include TRF420 and TA07 MS center pulley, TB-05 center shaft.
• utilizing ball bearings instead of synthetic and metal bearings provides better components fit and more efficient rotation.
• These ball bearings use plastic seals as opposed to metal ones – this enables you to start them around neat and work with them.
• Low-friction oil is employed to lubricate the internal workings.