This instrument is based on a style of panpipes found in viking-age archaeology in York and in several roman sites.
This version has nine pipes, C D E F G A B C D. The nine pipes are sufficient to play many medieval songs, as well as, for example, many of the dance tunes from Thoinot Arbeau's "Orchesography". The extant instruments are only fragments, so it's unclear how many pipes there should be.
A convenient thong hole allows the pipes to be tied to the belt of your T-tunic, or worn as a pendant around the neck.
Clare, Henrietta (1993). Roman panpipes found in London. London Archaeologist, 7(9):87-92