Duet Inventions These intermediate duets are perfect for developing endurance, agility, and musicality in a variety of styles. The 29 duets in this 59-page volume give trumpeters lots of material to work with and keep things fresh. These versatile pieces can be used for a variety of purposes, including performance, masterclasses, lessons, and of course, just for fun. Take a look at the free duets provided in the samples, and then have a copy of the entire book sent to your door.