Seamless, roto-molded vinyl balls are designed to allow air to escape slowly rather than burst, even if the outer skin is punctured. Great for strength, balance, and stretching exercises. Tacky surface enhances control. Burst-resistant to 1,000 lb (453.5 kg), but supports static loads of up to 2,200 lb (998 kg). Available in Sets of 6 or in convenient 6- and 12-Ball packs convenient packs a Magnus™ ABS Rack and UltraFit™ Training Charts.