Developed by law-enforcement specialist T. Kubota as a police aid, the "Kubotan Keychain" when used in the manner shown in this training manual, is a superior self-defence implement currently being carried by thousands of informed citizens world-wide. --- from book's back cover
If you own one of ASP's Palm, Key or Street Defenders, this book is an absolutely must-have. I have taught many women's self-defense classes based specifically on this book. There are other books out there, but this one is by Takayuki Kubota, the creator of the KUBOTAn. Hard to find and out of print, but worth the $25 you may have to pay for a copy. Cold Steel also has a similar defense product called the Koga and the Mini-Koga. There are many "Kubotan" like products out there. This book has great step-by-step techniques, none of which are complicated or difficult to understand. Review this book every half year, and you will instinctively respond when you must.