Lightweight at 2.2 lb, The microKEY2-37 from Korg is a slim USB-powered MIDI controller with a pitch wheel, a mod wheel, and a set of 37 velocity-sensitive Natural Touch mini keys.
An assignable 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 includes the Korg Software Bundle. Finally, purchasing the Korg microKEY2 will allow you to download a limited version of the Reason DAW.