• Piano Accordion Keyboards vary from 26 / 34 / 37 / 41 / 45, depending on manufacturer. They can be less than 26 or more than 45.

• Piano Accordion Standard Bass Keyboards vary from 48 / 72 / 96 / 120, depending on manufacturer. They can be less than 48 or more than 120.

• Button Accordion Keyboards come in various systems
  • "C" in the 3rd row
  • "C" in the 1st row
  • The button keyboard is also shown in catalogues as the number of buttons and actual number of notes
    eg. 105 / 64

• The Free Bass-Converter Bass Systems are also shown in catalogues as the number of buttons and actual number of notes eg. 120 / 58.