Breana Geering Pro Model Set of 8 Bearings Deep Groove Raceways: Balls roll deep in raceway channels, reduces side impact damage and breakage. Straight Edge, Removable Frictionless Shields: Pop off resistant, hold oil in, dirt and moisture out, and easy to clean. Micro Groove Raceway Surfaces: Linear micro-groove surfaces improve bearing lubrication, speed, and spin. Max Impact Cage Design: Non-distortion custom cage keeps the balls precision spaced. Micro grooves aid in oil circulation. Balls Out Technology: Eliminates shield and cage contact on impact for a go fast, stay fast bearing. High Speed Oil: Custom engineered light oil lubricant is water, oxidation, and corrosion resistant for extended wear protection. Factory Fresh Quality: Nitrogen-filled shrink wrap, reduces metal & oil oxidation until ready to be ridden.