Gym Ball Plug. Stopper for most Gym, Birth, Yoga, Swiss BALLS etc This is a standard plug that fits the majority of inflatable gym balls, including Reebok, Gymnic(all types), Birth-ease, Fitball, Tesco, Tunturi, Pro Fitness, Everlast, Lonsdale and many more Fits hole approx 5/6mm diameter. Approx 6cm long Hole starting at approx 14/15mm and graduating down to 5/6mm