We bought 6 for a small 6 boys (age 10-11 boys) party! Kids love the balls, no matter whether it is their first time to play with the balls. The weather was bad --- after a few hours rain and was still raining. But all kids just wanted to play them.The 4-ft balls are right size for them. But they are still little heavy for them for long time. They played about an hour with outer cloth wet, due to both rain and sweating. If we had known this, we would just bought 2-3 balls, i.e. 2-3 kids to share a ball. Kids really enjoyed the fun ---- especially rolling from the small hill; "it is like Roller Coaster, but it is not", that's one kid's saying.The ball quality is very good --- you can tell from the weight and touching. We will keep them for kids sports team activities/parties. Time will tell whether the quality lasts. It is definitely worthy of the investment.It takes about 3 minutes to fill the ball. The typical 3-size air pump will do the job; the middle one/size fit the ball inflation connector perfectly.
Douglas 
