. genuine Shimano Hollow Tech II bottom bracket assembly. set includes left and Right hand cups, spacers, inner cover, and inner o-rings. light weight seal structure helps to remove vital grams. sealed cups keep out dirt and water. maintenance free. compatible with 68 mm and 73 mm shell. durable Black anodized finish. easy installation. use Tlfc34 or Tlfc24 in conjunction with Tlfc36 adaptor tool for installation and removal.