My 8 year girl needed to advance from the green ball, and this was the perfect bridge to the regular ball. It is lighter and bounces lower. I think this can also work for the adult beginners.
I bought these tennis balls for my 9 year old son. We now have longer and fun rallies. Since these balls are more forgiving he can focus on his technique. It did take a little getting used to having the balls bounce a little less, however I highly recommend these tennis balls for juniors.
These balls are great for slowing down the game enough for beginners to get their strokes right