Roland DP-2 Damper Pedal
The DP-2 and DP-6 are momentary footswitches for "non-latch" operations such as sustaining notes on electronic keyboards. The DP-2 is a compact model that can also be used for things like punch in/out on Roland/BOSS recording gear, while the DP-6 (not shown) is a larger, piano-style pedal.