An older medical droid that serves the Rebel Alliance, it is a skilled surgeon and field medic. Too-Onebee treats Luke Skywalker twice around the time of the Battle of Hoth, including an operation to replace Luke's severed hand with a mechanical replacement.

Like others of its class, this roughly humanoid-appearing droid has surgical manipulation appendages, a medical diagnostic computer and a treatment analysis computer. For detailed patient status information, 2-1B relies on medical instrumentation or useful analysis droids like FX-7.