Enduro\'s ABEC 5 is the next performance step up from the popular ABEC 3 range. By using military level, high precision HRC-64 hardended Grade 5 Chromium Steel Balls, and 52100 High-Carbon Chromium-Alloy mirror polished races. This combination allows Enduro\'s ABEC 5 bearings to use tolerances twice as tight as ABEC 3, and operate without any noise. The Graphite/Nylon ball retainers allow virtually frictionless movement and provide constant lubrication to maximise the life of the bearing.Key Features:Bearing Code: MRA 2437,Dimensions: 24mm x 37mm x 7mm,ABEC: 5,Grade: 5,Seals: LLB,Grease: Kyodo Yushi PS-2,Application: Hubs, Bottom Brackets,Weight: 31.10g.