The alto model of the popular Studio 49 1000 range encompasses middle C through to A61 and includes Bb and F# note bars which you can swap out in order to play in different keys. Each note bar is 30 x 6 mm in size and made of aluminium for a resonant sound quality. Each bar is engraved with the note name and sits on a textile-coated bar for longevity. Studio 49 have patented the design of their sound box which has a number of different resonance chambers which help make this model sound richer than it might otherwise. You can also purchase the model 49-HAM1000
which is the chromatic half and when paired with this diatonic model creates a fully chromatic instrument.