I blew these up today for the grandsons to play with them in the trampoline and they were out there for hours. They come with a pump and they blow up real easy. They are a good size and feel like a rubber and they bounce really good. Our plans are to let them use them in the pool. I love how they come with 6 balls and each a different color and there is even a smooth blank spot to put a name. So much fun!