The sram bottom bracket gxp blackbox cups are built with sealed ceramic cartridge bearings this sram bottom bracket is extra light durable and can be easily maintained ideal for all road cyclists this part will ensure your pedals are kept insulated and turning smoothly the gutter seal technology vastly improves sealing against dirt and water whilst reducing seal drag two bicycle specific cartridge bearings and eight seals have been used on the gxp system to ensure a smooth and long la