Jolly Mega Ball by Horsemen's Pride. This heavy duty inflatable ball is made specifically for horses. This durable exercise ball that can be used for enjoyment or training and is a favorite of Natural Horsemanship practitioners. Jolly Mega Ball Cover by Horsemen's Pride. These covers are made as a decorative and protective cover for the Jolly Mega Ball. Jolly Mega Ball Cover by Horsemen's Pride. These covers are made as a decorative and protective cover for the Jolly Mega Ball. They come in three sizes and designs compatible with your Jolly Mega Ball. ***** Green Mega Jolly Ball must be FULLY INFLATED to properly fit wtihin the cover. Please note if the Green Mega Jolly Ball is "too small" to fit the cover, YOU MUST ADD MORE AIR TO PROPERLY AND FULLY INFATE THE BALL*****