For someone like me, a (hopefully) future Navy SEAL, this is amazingly useful. Pocket sized for going anywhere, cheap and very deep explanations. Every exercise category has the different resources you might or might not need, and all types of tips, perfect forms and explanation on how to complete a exercise, videos and pictures, just so much detail! Perfect handbook and app for everything you need for training. Very worth $ 1.99 (also the $.99 for nutrition is very useful too).