Already you have the best choice for transmissions of 1 × 12 MTB? Get it now with the new GENERAL LEE Cassette 12V 9.50 XD Ask for it at your store of confidence and do not miss all its advantages. The broader range of market development 533% Minimum weight 344 gr High durability (steel machined from a solid block hardened and treated) New and enhanced phase shift tooth Shark Fin , with a running silent , precise and very fast Replaceable any of the component parts (pinions steel, aluminum last two pinions, nut and cap) Scaled progressive 9-11-13-15-17-20-23-27-31-35-41-50 9 makes the difference