p-i-l-a-t-e-s Core Stability Ball Instructor Manual Levels 1 - 5The p i l a t e s Core Stability Ball Instructor Manual contains 76 detailed exercises. A challenging piece of equipment, the Core Stability Ball gives you a fantastic workout due to it's multidirectional movement capacity. This manual is the final of the 27 p i l a t e s Instructor Series, currently the largest Pilates exercise resource in the world.