What a soft tennis ball is like
Rubber, hollow and inflated. It weighs 30–31 g, measures 66 mm across with a 1 mm tolerance, and bounces to 70–80 cm when dropped from 150 cm. That is what ISTF rules require. A tennis ball has almost the same diameter, about 67 mm, and weighs about 57 g, almost twice as much.
Kenko balls are made of natural rubber and have a valve through which you top up the air. The official TSOW-V ball is approved by the Japan Soft Tennis Association (JSTA) and made in Japan. The rules speak of a white ball; the yellow one has the same approval.
Training or tournament balls
The Kenko TSOW-V tournament balls are the official match balls. The white TSOW-V is played at PSTA and ISTF events, the yellow TSOY-V has the same specification and is easier to see indoors and on a light court. The tournament ball is for matches and for advanced players who want to practise with what they later play tournaments with.
The Kenko Standard training balls have the same weight and the same diameter. A beginner will not feel the difference. According to Kenko the difference is in the percentage of balls that fly straight, and advanced players notice it in a match. For club practice the Standard is enough.
The cheapest ball in the shop is the Kenko Reasonable TSRW-V. It is for drills that use a lot of balls, such as serving from a basket or a group lesson.
Which soft tennis balls to choose to start
A box of 12 Standard training balls, white or yellow. White is the colour played at PSTA events, yellow is easier to see indoors. That is the box we put in the starter sets. Tournament balls come later, when matches start.
Coloured soft tennis balls
The pink, blue and black Kenko Standard balls are the same model as the white and yellow ones, in a different colour. They are for children and schools, because they are easier to see, and with a group of children they are simply more fun. PSTA events are played with white balls, so the coloured ones stay in practice.
How many balls to buy
For two people practising, a box of 12 is enough. Kenko balls come in packs of 2, boxes of 12 and a basket of 120. In a box of 12 a single ball costs less than in a pack of 2. The basket of 120 is for clubs, schools and coaches. The group set, four rackets for one doubles court, has 24 balls, a box for each pair.
How to inflate soft tennis balls
With the Kenko pump, whose needle goes into the valve the way you inflate a volleyball. Push the needle in straight, because needles break when inserted at an angle. Kenko recommends this pump for its valve balls and states that it is only for soft tennis balls. Inflation instructions are in the photo gallery on the ball pages.
Pressure holds for a few weeks, then a few strokes of the pump are enough.
How to check the pressure in a ball
By the bounce. A correctly inflated ball dropped from 150 cm bounces to 70–80 cm. Experienced players squeeze the ball in their hand and inflate by feel. To inflate a whole basket evenly before a match there is the Kenko 66 Air Gauge, which checks that the ball has the regulation 66 mm diameter.
Balls for a club and a coach
Clubs and coaches buy balls in the basket of 120. The Kenko basket is also sold on its own, polypropylene, about 35 × 50 × 24 cm, and there is a nylon Kenko carry case for moving a basket full of balls. Before a match the whole basket is inflated evenly, which is what the Kenko 66 Air Gauge is for. Clubs and schools buy on invoice at wholesale prices, the details are on the clubs and schools page.
Which balls to buy
To start and for practice, a box of 12 Standard balls, white for PSTA events or yellow for indoor play, and a pump. For matches, a box of TSOW-V tournament balls. For children, coloured Standard balls. For a club, the basket of 120 and the gauge. All models are in the balls category. Balls also need a racket, and that has its own guide, how to choose a soft tennis racket.
Kenko balls, training, tournament and coloured
See balls