The MPD32 is a MIDI controller based on the very popular MPC drum machine created by Akai. The 4x4 drum pads look and feel very similar but there is no audio capabilities with this device. It is purely a MIDI controller.
In addition to the 16 rubber drum pads the MPD has 8 faders, 8 buttons, 8 endless rotary encoders, transport controls, controller bank switches, 32 preset locations, foot control inputs and a MIDI clock.
The MPD32 can operate as a Control Surface in Ableton (and possibly other applications) allowing the top faders to auto-map to the first 8 tracks and the below buttons can control the ARM function of these 8 tracks. Additionally, the 8 encoders will auto-map to the first 8 MIDI assigned controls in a rack or macro controls without learning. The pads themselves will automatically map to the pads shown in Abletons drum rack and will follow you through as you click through the rack.