The Anglo concertina is a diatonic musical instrument. This means that it only has notes of a certain key. The diatonic nature of the instrument is what makes it different from the English concertina. Twenty-key Anglo concertinas have two rows of five buttons on each side. The two rows are those of two different keys, C and G being the most common. As one plays up and down a certain row, notes from the scale of that single key are produced.

Each button also produces two different notes, depending upon whether one pushes or draws the instrument. This is done by positioning two reeds of different tones in opposite directions. When the instrument is drawn, air flows into the instrument and makes the first reed vibrate. When the instrument is pushed, air flows out of the instrument and makes the second reed vibrate.

The thirty-key Anglo concertina has an extra row of five buttons on each side of the instrument. This row does not have the notes to the scale of a certain key, but rather a mix of accidental notes that are not present on the other two rows. These extra notes can allow the musician to play in keys other than the two provided.

Anglo concertinas are used mainly in folk music. The diatonic nature of the instrument and the nuances resulting from pushing and drawing the instrument make it well suited to playing jigs, reels and hornpipes. This effect has made them very popular in Ireland, and they can be heard in many Irish folk and traditional recordings.
