Mid Air 25 Key Wireless Midi Keyboard Battery Operated
By M-Audio. Comes with USB Receiver and is battery or wall adapter operated. Battery Life is 20-30 Hours!
Connection is easy — plug the Mid Air's receiver into a spare USB port on your computer, switch the keyboard on (which illuminates an almost blinding three-digit blue LCD) and hit a few keys, which should cause an LED on the receiver to light up, confirming that MIDI data is being received. Adjust the appropriate MIDI input settings on your sequencer or software instrument, and hey presto, you're up and running.