you need this style

https://www.amazon.com/Penn-Jumbo-Tennis-Ball-Basketball/dp/B000LECJAO/ref=pd_lpo_vtph_200_tr_t_3?_encoding=UTF8&psc=1&refRID=2TRA7FSAPQRD3HXK9ZMZ

Its made of the same material as a tennis ball so its kinda hard and you cant kick it directly in his direction but it won't pop in an hour. dunno if u can get them cheaper