They are descant instruments in C (A=440) with a tuning slide to allow players to tune up or down to suit the vagaries of pub sessions.The tuning slide consists of telescoping brass tubes which make little difference to the bore diameter when the slide is pulled out. There are limitations as regards the instruments internal tuning but you can expect satisfactory performance within a semitone of concert pitch.
Built in Mopane or African Blackwood and occasionally other timbers, with a tuning slide and silver plated ferrule
these recorders produce a good carrying tone with wonderful volume
suitable for the loudest session.