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This book "teaches" two rolls (picking techniques) for the banjo. The forward roll, which is the most basic, and the "7-note" roll, which I've not seen before, and is not materially different than a forward-reverse roll. That's it! 2 basic and very rudimentary techniques. The rest of the book is devoted to text that suggests ways to approach learning, and not much else.
Save your money. This is as far from an instruction manual on warm-ups as you can get. Look online for the free information on banjo picking techniques, and banjo techniques to improve your speed, and you've already found more than this book will sell you.