From Boss:

The RC-20 Loop Station is the first compact phrase recording and sampling pedal that's actually easy to use. A long sampling time of up to 5 1/2 minutes, helpful Guide Click and Loop Quantize functions, Realtime Tempo Change and hands-free control make the RC-20 a "must-own" pedal for musicians looking to create and play back loops "on the fly."

• Guide Click and Loop Quantize functions for quick, easy creation of perfect loops using footpedals
• Realtime Tempo Change function allows for changing recorded samples' tempo without changing pitch
• Overdub function allows for creation of "sound-on-sound" loops
• Stores up to 10 looped phrases and 1 "one-shot" phrase, even after power-off
• 5 1/2 minutes total sampling time
• Mic input, Instrument input and Auxiliary input for sampling vocals or pre-recorded audio–even simultaneously
• Auto Start begins sampling automatically with incoming audio
• Reverse sample playback on the fly

comes in original box with manual , no power supply