 Hammond used a 25-note pedalboard because he found that on traditional 32-note pedalboards used in church pipe organs, the top seven notes were seldom used.The Hammond Concert models E, RT, RT-2, RT-3 and D-100 had 32-note American Guild of Organists (AGO) pedalboards going up to the G above middle C as the top note.The RT-2, RT-3 and D-100 also contained a separate solo pedal system that had its own volume control and various other features.