Hope T-Rex 40T SR Silver SRAM Ratio Expander Sprocket 1x Cassette Conversion 

Manufacturer blurb below:
  • Allows you to upgrade your existing 11-36 10spd cassette to give an 11-40T range
  • T-Rex installs behind your existing cassette and replaces one of the smaller sprockets, usually the 17T
  • Precise matching of the tooth profiles and shifting points specific to each cassette
  • Perfect mating of supporting tabs to reduce flex and aiding shift performance
  • Lower B-tension adjustment is needed ensuring good shifting throughout the cassette range compared to fitting a 42

Light signs of use.

Sold as pictured. What you see is what you will receive.

Thanks for looking