Keys on O'Riabhaigh Pipes are generally made from stainless steel. The wooden blocks upon which the keys are mounted are sleeved with either stainless steel or brass to increase durability and longevity. Keys are becoming increasingly popular on chanter as pipers experiment with new ornamentation and repertoire. Available keys include Cnatural, Fnatural, Gsharp, Bflat and Csharp. The most common key configuration currently among pipers, in my opinion, seems to be a two key  setup (Cnatural and Fnatural). If you're planning to play in the increasingly popular key of A, then you should also consider the Gsharp key. The Csharp key is a nice way (but not the only way) of hitting the 3rd octave D, while the Bflat key is useful in more unusual tunes and in ornamentation.