Perfect for intense strength, balance, and flexibility exercises using stability balls. Slowly and safely deflates if outer skin is punctured. Burst-resistant to 500 lb but supports static loads of up to 1,000 lb. Includes hand pump inflator kit. Available individually or in convenient packs with storage and instruction. Multi-Size 6-Ball Pack includes two 55 cm, three 65 cm, and one 75 cm; Multi-Size 12-Ball Pack doubles the quantities.