This instrument plays really well. It's a C# and has really rich harmonics, kind of gravely. Overtone/toot can be played quite easily. It look is deceiving~it has quite a booming voice...
It's almost 55 inches long and has a fairly narrow bore, approx. 2 inches at the mouthpiece and the last 5 inches clearly has been opened. Between mouthpiece and end the bore looks untouched consequently it's diameter varies. It's external shape is conical with only a slight taper. Mouthpiece end is approx 6 1/2 inches (circumfrence) and the distal end is approx 9ish inches.... It's a very heavy instrument....
Looking at the exhibition page on Guans website I saw this instrument ( bottom of page linked below) which looks similar in shape and is low pitched as is the Old mans stick...
http://www.ididj.com.au/exhibitions/ncal.html