Jolly Mega Ball Designed for extra durability for horses of all sizes. Anti-burst design can withstand up to 2,500 lbs. of pressure. This allows you to inflate the ball to it's full capacity without hesitation. Includes informational brochure for proper inflation and care. To check if your Jolly Ball has been inflated to full capacity, stand inflated ball upright and measure the height. The medium (blue) ball should measure 30" high and the large (green) ball should measure 40" high. It they are not the proper height, continue to inflate. It is important to know balls that are not inflated, can not be measured with accuracy, as the anti-burst material of the ball stretches out.