These are known as the Jugs pickleballs. While all balls are acceptable for indoor or outdoor play, these are typically used for indoor play. These are approved by the International Federation of Pickleball (USAPA/IFP).
Jugs Bulldog brand pickleball/baseball
Durable Poly ball used for pickleball and baseball
Traditionally used for indoor pickleball play but can also be used outdoors
Popular in community centers and athletic clubs
USAPA/IFP approved for tournament play as of 1/16/2017