I would recommend this product to two types of people; a) experienced musicians who want a small midi controller to take down basic ideas whilst on the move and b) beginners who have progressed beyond the point of solely using samples and who want to add their own melodies to their music. The unit measures appox 33.5 x 9.5 cm and will easily fit into a backpack and/or fit snugly next to a laptop on a table. There are 25 mini keys of the sort seen on small electronic keyboards. These measure approx 8 x 1.8 cm (for white keys) and 4.5 x 0.7 cm (for the black keys). Small but playable. Although there are only 2 octaves the octave down/up feature allows access to the full range of notes on a standard sized keyboard. The power source is a standard usb cable (included) so there is no need to plug it into a mains socket. Installation was straightforward and the unit was recognised straightaway (no extra drivers needed). Note for 1st time midi users; once you have selected the LPK25 in your music software (DAW) midi menu option you may have to restart the program in order to hear sound. How useful is the LPK25? Basslines, simple melodies and some basic chord progressions are all playable with this unit and also its possible to work up some ideas on virtual drum kits. The keys are touch sensitive so you can get a degree of expression into the tunes though i suspect the level of sensitivity wont satisfy experienced keys players. An adjustable arpeggegiator is also included (useful as some virtual instruments dont carry this feature) and a sustain button which can be used with some piano emulations. Overall the LPK25 is good value for money and i would recommend it, especially to those starting out with music software.