The Core Secrets Program uses Gunnar Peterson's 1-2-3 Core Technique to help whip you into shape. Every workout incorporates a fitness ball to work your upper and lower body, as well as your core. Included are four different workouts and everything else you need to get started on your new fitness program. A happier, fitter and stronger you awaits. By Guthy-Renker. Fitness ball measures 23" x 23". Comes in the original box. DVDs are still sealed in original wrapping as is ball and pump. Please note, the first image is a stock image to show the ball inflated.