The MPD18 from Akai Professional is a 16-pad USB MIDI controller. It enables you to trigger MIDI notes through USB with any MIDI assignable software. The 16 velocity and pressure sensitive pads react in a very musical manner, giving the user very precise control when triggering commands.
When it comes to pad-style drum triggering devices, there is no product line more well-known for this than Akai Professional's MPC series. What the MPD18 has set out to do is to provide users with MPC-style trigger pads in a compact, bus-powered USB form factor.
The MPD18 features MPC Note Repeat, which is a function found on the MPC series which enables you to quickly create repeating triggered notes, often used for drum rolls and hi-hat beats. You aren't limited to just the 16 pads on the face of the MPD18. You can assign sounds to 3 different banks of pads, for a total of 48 triggers.