"Diabolo 3, Two Hot to Handle" is a book that covers advanced tricks and techniques for using two diabolos. The book is written by Donald Grant and Guy Heathcote, who is one of Europe's top diabolists. The book is intended to show most of what is possible with two diabolos, and suggests that anything that can be done with one diabolo should be possible with two. The book also mentions that three diabolos is somewhat harder to use, but provides a starting point for those who want to try. If you are an experienced diabolo player looking to learn advanced tricks and techniques for using two diabolos, this book may be a helpful resource. It may be a good idea to review the contents of the book before purchasing it to make sure that it covers the specific topics that you are interested in learning about.