Trinity College Concertinas are handcrafted instruments and authentic reproductions of the instruments introduced in the early 19th century in England and Germany. Trinity College offers both of the two major types-the Anglo and the English models. The English style of concertina operates on a "unisonoric" system where each push and pull of the bellows gives the same note when any given key is held down. The English System alternates the notes of the scale between two hands, enabling the execution of rapid melodies. The English System style concertina is quite versatile and can be used for many styles of folkdance music as well as Classical music in the hands of a virtuoso. The player holds each side of the instrument with the attached thumb strap-as opposed to the Anglo style instrument where the straps cover the entire hand.