Bearing 17287 coated - Inner diameter 17 mm / Outer diameter 28 mm / Thickness 7 mm. The components of the bearing are made from materials that allow for a particularly smooth, frictionless construction. The balls are housed in a polyamide cage. Each ball is optimized with Ceramic Speed Low Viscosity grease to minimize friction and extend lifespan. Additionally, dust caps are included to keep dust out. These bearings can be used in any discipline: road, time trial, triathlon, track, cyclo-cross, and mountain biking. The benefits include reduced friction, improved power transfer, and increased durability. Ceramic Speed balls glide 400% better and are 58% lighter than standard bearings in the cycling industry. Each bearing is hand-checked four times to ensure perfect positioning. Designed and assembled by hand in Denmark.