Incl. 2 x sealed ball bearing. Dimensions 1" ID x 52mm OD x 21mm wide. OEM replacement reference 9247. Note: These All Balls Racing bearings are high quality high speed wheel bearings. Manufactured to ABEC 3 precision levels. Bearings are lubricated with a Chevron fabricated high performance; high temperature grease of SRI 2 level that contains anti-rust and anti-oxidation additives. Compatible with temperatures of -20°C to +150°C and rotational speeds in excess of 10.000 RPM. Triple lip seals are used to help prevent water and debris entering the bearing.