Uilleann

cut/pasted from the Bagpipes page

The next most common type is the Irish or Uillean (pronounced illin) bagpipe; this or the Northumbrian bagpipe is generally claimed to be the most developed bagpipe in existence. This bellows-blown pipe plays a two octave diatonic scale in D major; it also has a C natural, allowing tunes to be played in G. With the addition of extra keys to the chanter, other modes can also be used, although these are less common. The most commonly added keys are a C and an F natural key. The Uilleann pipes also have three drones, set in a common stock, all tuned to three different octaves of D, and up to three regulators which are effectively a kind of chanter with keys, designed to be played by the wrist. Accomplished players can use these to provide a limited but powerfully impressive chordal accompaniment. Often Uillean pipes are found without any drones or regulators; these sets are called somewhat misleadingly "practice sets". In fact, many pipers use these sets for their entire piping careers. Another common choice is to have only the drones, without regulators. This is known as a half-set. A final occasional variant, the three-quarter set, omits the bass regulator, which is less commonly used.