ENDURO® CH SERIES CERAMIC HYBRID CARTRIDGE BEARINGS Grade 5 ceramic balls ABEC 5 cartridge rating Dual-lip seals Compare ENDURO Ceramic Hybrid Bearings with any other brand. Nobody can approach there specifications anywhere near there price... THE BALLS are made from pure Silicon Nitride material with extreme high density from uniform compaction (3.25 g/cm3). The micro-structural development of this material during manufacture is second to none. These high precision Grade 5, SI3N4 pure ceramic balls are 5/1,000,000” from exactly round in sphericity. They are 60% lighter in weight, and 7 times harder than steel. Friction is reduced to near zero. THE RACES start with vacuum de-gassed alloy hardened to Rockwell C-64. These high precision races are cryogenically treated not once, but three times during the final "super polishing" phase. Cryogenic treatment means taking the races down to minus 300º Fahrenheit to nomalize the crystalline structure of the material so that the races will resist the hardness of the ceramic balls and get the maximum wear potential. This critical treatment to the races is left out by many manufacturers, but not by Enduro. THE RETAINERS are nylon with Graphite and are virtually frictionless. THE SEALS are "LLB" low contact labyrinth type, with 2 sealing lips which fit into a matching groove on the inner race. The outer sealing lip repels dirt and water while the inner sealing lip retains the grease. When the bearing is first turned, you will notice some grease will come out of the seals. This fills the chamber between these 2 sealing lips, forming a “hydromatic seal.” Seal material is NBR rubber.