Wilson US Open Extra Duty Tennis Balls - 18 tubes - 72 balls

Pressurised balls are filled with air and play livelier, which is why matches are played with them, but the pressure escapes within weeks of opening the tin whether you use them or not. Pressureless balls take their bounce from the rubber itself, so they last far longer and get better as the felt wears in. They are the sensible choice for ball machines, coaching baskets and practice.

A tin of pressurised balls is at its best for around two to three hours of play, and noticeably flat after a few weeks of being open. Serious players open a fresh tin per match. For casual hitting, most people play on with balls long past the point where they have gone dead.

They are the stages of the junior pathway. Red balls are the slowest and lowest bouncing, then orange, then green, then a standard yellow ball. Using the right stage means a child can actually rally rather than chase, which is why coaching programmes are built around them.

They look the same but sit at different pressures. A padel ball is slightly softer and bounces lower, which is what makes the padel game controllable. Using tennis balls makes rallies much harder than they should be, and is the single most common mistake new padel players make.