Trinity College Concertinas offer all the features and craftsmanship of the classic turn-of-the-century instruments but at moderate cost. These instruments are light weight, portable, easy to learn and fun to play. Trinity College Anglo Collection Concertinas feature a diatonic button system, which works much as a harmonica does. Each button produces two different pitches, one on the blow another on the draw. Though they can be played in other keys, they are mostly played in C or G. Harmony may be obtained by pushing more than one button at a time.