This HandSonic HPD-15 comes with its original power supply plus a long custom midi harness, and the dedicated Roland stand-mounting adapter plate kit, which is a $40 accessory.
Derived from V-Drums technology, the HPD-15 allows hand percussionists to play any of 600 realistic internal acoustic and electronic percussion sounds, plus some other instruments - 15 simultaneously, using its 15 touch and pressure sensitive finger pads, plus two ribbon controllers and a "D-beam" infra-red proximity sensor over which you can just wave your hand to activate. It's pretty amazing. And... all of these sounds are programmable, and tweakable using surface control knobs in real time.
The ribbon controllers can send real time pitch bend, there is a hold button to play a background chord or drone, and a very realistic roll function that sounds natural, unlike many modern "fast strike" digital "rolls" that simply play 32nd or 64th notes. Flams and accents can be played quite naturally with your hands due to the extreme speed and sensitivity of the finger pads, plus the physical space to use both hands at once, as when playing real drums. The whole experience is of a quite natural and realistic percussion performance. The pads can also of course be played with sticks if you choose.
I've used this unit for many, many years, so it has its share of nicks and abrasions. But functionally everything works as it did when new from the factory. You can find the manual online at the Roland website.