Follis (ball)
Follis (a term used in Ancient Rome), or Ball of wind (pilota de vent in Catalan), a term used in the 15th and 16th centuries in Spain and Italy, was a hollow ball inflated with air under pressure, able to jump and bounce when impacting at a certain speed with any solid body. Different types of balls of wind were commonly used to play a variety of ball games that were popular in that particular period of time.