GoFit Professional Grade Stability Ball - Home Workout Supplies The GoFit Professional Grade Stability Ball is a round, unstable surface, so you not only train the primary muscle groups but also the smaller stabilizing muscles as well. PRINTED EXERCISE- The Professional Grade Stability Ball has exercises printed directly onto the ball, making this stability ball a fun, yet challenging way to stretch, tone, and tighten your body! TOTAL WORKOUT - The GoFit Pro Professional Grade Stability Ball and Training DVD plus manual is very efficient, allowing you to see the results you want in a much quicker period of time. INCLUDES - Included with the Professional Grade Stability Ball is a Brook Benten Training DVD, training manual, ball plugs, ball plug remover, foot pump, bicycle pump adapter, and measuring tape. SIZES - The 55cm (blue) Professional Grade Stability Ball is recommended for persons 5 to 55, the 65cm (red) ball for persons 55 to 6, and the 75cm (silver) ball for persons 6 and over.