Rotor InPower Power meter crank. Crank arm length 172.5. Used for a couple of seasons, wear and tear is consistent with usage. Uses one double AA battery that you insert into the spindle. Very good condition and operates as it should. I selling because I switched to using shorter crank arm and the arms on this model can not be swapped out. This sale is for the crank only. Does not include the rotor DM chainrings. Power meter can be set up using the Rotor app.