Shimano HG Hub compatible single speed conversion kit with ramped spacers. Black anodized.Includes: 2 - 9mm angled spacers 6 - 3mm spacers 2 - 1mm shims 1 - lockring 1 - 20t cogCompatible with: Any ½ x 1/8 pitch chain, this includes BMX and Track chains Any 8 or 9 speed chainDoes not work acceptably with:: Any 10 or 11 speed chain