Jumper exerciser with door clamp is sturdy and scientifically designed for use with appropriate door frames. It gives your baby complete movement and provides easy, natural breathing. Babies build strength, balance and coordination safely and comfortably. Babies can use their Jolly Jumper exerciser as early as 3 months (only if baby can hold head up with full neck support) to walking age, with baby's maximum weight of 28 lbs (13 kgs). The door clamp may be used only on frame openings as shown on the illustration below. Wall thickness should have a maximum thickness of 6 inches or 15cm with frame mouldings having a flat top surface of no less than 1/2 inch or 1.25 cm. Door clamp is included.