its a concertina,There is another technique that I use.The turning of a quaver into two notes.I play the first one short and the second one longer as if I was playing a grace note before the second note ,but the notes are of the same pitch, I do this using two different fingers , and often when the note to follow is on the opposite side [so example] three quavers e a a, e on the left becomes e e followed by a a on the right,or it could be e[quaver]aa.. a more of this in the [concise english concertina tutor] by Dick Miles.Dick Miles.