Claris is Shimano's new entry-level road group.
This version of the rear Derailleur features the short-length "SS" cage.
(See Capacity in Sheldon Brown's Bicycle Glossary if you have questions as to the capacity you need.
This is nominally an "8-speed" unit, but works fine with 5 thru 8 speeds as long as the shifter matches the number of gears in back.
We recommend replacing the inner shift cable if you are changing the Derailleur.