Ultra Bearing 10x15x4mm (4 pcs.)
4 pieces ca. 10x15x4mm Ball bearing
The Ball bearings all have one steal sealed and one rubber sealed side.
The rubber sealed side is used for maximum protection from dust and dirt.
The steal sealed side is used for maximum smoothness.
Our recommendation: The rubber sealed side should always be mounted that it faces outwards. Example Hub Bearings: The rubber faces outwards, the stealside faces inwards.