These original duets by Keri Degg are really good. Each little piece has a title and an easy-to-understand explanation of what the challenge might be. This could simply be an emphasis on dynamics or tonguing, but also includes the more adventourous such as experimenting with a variations of speed, or altering the peformance direction to change the style. The tunes are split between the parts and there is a special symbol to indicate that change and also to warn of a potentially difficult manoevre. The book is progresssive and the grade 5 level reached towards the end is really quite difficult. Sightreading these at a higher level extends the book's use even further. There is a lot of material for your money here and you won't regret adding this to your repertoire.