Lightweight at 2.2 lb, The microKEY2-49 from Korg is a slim USB-powered MIDI controller with a pitch wheel, a mod wheel, and a set of 49 velocity-sensitive Natural Touch mini-keys.
An assignable switch jack affords you the ability to use a sustain pedal, while two octave-shift buttons allow you to change the range of this three-octave unit. You can make edits to MIDI parameters using the Korg KONTROL Editor software, which is available for free download on the Korg website. This can be useful in customizing the microKEY2 to your specific sensibilities, such as adapting the instrument's velocity curve to your individual touch.
The controller also includes five virtual instruments (Korg Legacy Collection, UVI Digital Synsations, AAS Ultra Analog Session, AAS Strum Session, AAS Lounge Lizard Session) and two apps (Korg Module LE for iPhone and Korg Module LE for iPad). Finally, purchasing the Korg microKEY2 will allow you to download a limited version of Propellerhead's Reason.