[airair]

Since they are Henry's tennis balls they are his favorite color, the color of dirt.
As for being large, that's the point. It helps to visualize the angle of attack on the ball. I like to think of it as at 2:00 o'clock with the top of the ball being 12:00 and the bottom being 6:00.
I spent over 50 years being a scooper. I need things like this.

The part about the color was just for fun. White golfballs you know. But covered with dirt - that should also work.