The ROTOR T4730 Internal BB (Steel, Black) is a threaded internal bottom bracket engineered for bicycle frames with a T47 bottom bracket shell. It features steel ball bearings in precision CNC machined 7075 T6 aluminum cups with silicone seals for durability and smooth rotation. This internal design places the bearings inside the frame shell with only the flange protruding slightly, keeping a clean look and reliable performance. It’s compatible with 30 mm spindle cranksets, commonly used on modern road and mountain cranksets.