Hope T-Rex 40T Ratio Expander Sprocket - Black

The hope T-REx adapts a 11-36 10spd cassette to give an 11-40t range
T-REx ring installs behind existing cassette, replacing one of the smaller sprockets, usually 17t
Shimano and Sram specific tooth profiles and shifting

Compatible with:
Shimano XT and XTR 11-36 10spd cassettes
Sram PG1030, PG1050 and PG1070 11-36 cassettes

Colour: Black

Note: As you are taking out one of the middle sprockets, there will be a bigger jump between those gears - but you will benefit from increased climbng capability due to the lower gear provided by the 40 tooth sprocket.

Also note: You may need to increase your chain length to accomodate the larger sprocket