According to the manufacture, Gymnic Plus Stability Balls (also called Swiss balls, fitness balls, and exercise balls) are ANTI-BURST. "ANTI-BURST" means they don't explode; they slowy leak air if punctured.
Gymnic Plus Stability Balls (also called Swiss balls, fitness balls, and exercise balls) are safe.
According to the manufacture:
They ANTI-BURST and will not explode! If punctured, the ball deflates slowly.
Latex-free vinyl material has a soft, comfortable feel.
Heavy-duty ball for use in all training environments.
Holds up to 600 lbs.
Exercise sheet by JC Santana includes 40 exercises for body alignment, balance, and abdominal strength as well as chest, back, shoulder, leg, and hip strength.
Three sizes: Users up to 5'7" use 55 cm, users 5'8" to 6' use 65 cm, and users over 6' use 75 cm.
Select ball size so you can sit with knees and hips at 90 degrees.
Pump not included.
UNIQUE WATER-FILLED APPLICATION:
You can fill any Stability Ball with water (between 1/2 - 2 gallons) to add weight to the ball. The addtional weight provides the following:
Stability in static positions, such as bridges and push-ups.
Insability during dynamic exercises, such as chops and rotations.
Greater resistance for carry exercises, such as hoverhead holds and walks.