Works on bass too
The EBow is a hand-held electronic bow for guitar. This small battery-powered unit replaces the pick in the right hand letting the guitarist mimic strings, horns, and woodwinds with unbelievable sensitivity. The EBow produces a powerful infinite sustain, rich in harmonics for incredible guitar sounds. Unlike plug-in effects, the Energy Bow does its work on the string itself... Direct String Synthesis™. Infinite Sustain is just the beginning.
Demo on bass: https://www.youtube.com/watch?v=8SrFCgnKO3A