This is Tamiya 950 Sealed Ball Bearings 2 pcs. These are rubber sealed ball bearings, which offer smooth rotation, great precision of attachment and even simplified maintenance.
Material: Metal / Rubber
Using ball bearings in place of plastic and metal bearings gives better parts fit and more efficient rotation.
These ball bearings employ rubber seals rather than metal ones – this allows you to open them up to clean and work on them.
Low-friction oil is used to lubricate the internal workings.
Tamiya 950 Sealed Ball Bearings (2 pcs)