Shimano zee m640 shadow 10 speed rear mechthe zee rd m640 features shadow plus technology proven to reduce chain slap drop and impact noise and the 10 speed short cage rds low profile tucks safely below the cassette cogs with two spec options that enable a typical mtb cassette 11 32 11 34 11 36 or a close ratio road cassette 11 23 11 25 11 28 zee is ready to handle the needs of enduro and dh racers 10 speed also offers complete compatibility with dyna sys mtb product and shimanos latest