PRO 2 EVO‚ = 5 x Blueseal Bike Bearings ( 3 different sizes ). PRO 2 EVO SRAM‚ = 5 x Blueseal Bike Bearings ( 2 different sizes ). Blueseal Bike Bearings™ are Bicycle Specific Bearings. The tighter the seal is to the inner bearing race, the harder it is for water and dirt to get in — and the harder it is for grease to escape.
