PTP - The PTP CoreBall is a versatile pro-grade gym ball that can be used during core stability and flexibility exercises. In particular, using a CoreBall can help activate the muscles surrounding the abdomen, the pelvic floor and the back, which act as the important foundation to all functional movements and daily activity in general. This particular Steel Grey CoreBall is our largest CoreBall and features a 75 cm diameter, which makes it suitable for individuals who are over 185 cm (or almost 6 ft 1) tall. All our CoreBalls come with a bonus pump for added convenience.