Titanium balls

Penn tennis balls and other ball brands are now making balls with a specially formulated rubber that is blended with powdered titanium. The metal strengthens the bonds in the core and increases the playable life of the ball. Titanium balls will lose their liveliness over time (once the can is opened) like any other regular tennis ball, but they take longer to wear out on court.

Customized Cans

Cans of tennis balls are almost always labeled "Regular Duty" (for indoor and clay), "Heavy Duty" or "Extra Duty" (for outdoor hardcourts) or "Grass." Make sure you get the appropriate type for where you play.

Ball management

If the server needs tennis balls, the player closest to a ball should get it and send it to the server. Send a ball to the server so that he/she can catch it easily with one hand. Advanced players seem to be able to get the ball to bounce once, softly, to the server, but most less advanced players should make the ball bounce twice to ensure that it arrives at a low speed.

High Pressure

If you play 3,500 feet or more above sea level, get " High Altitude" tennis balls. They are not as highly pressurized as regular tennis balls, which, in the lighter air of higher elevations, can be too active.

Regular vs. Extra Duty felt

You should use a Regular Duty tennis ball on clay or indoor courts. Extra Duty balls last longer on rough, hard asphalt and cement courts. Or, you can mix things up. If you like a fast game, try using a Regular Duty tennis ball on a hard court. To practice your form and positioning, slow down with an Extra Duty ball on a clay court.

Pressureless balls

The ultimate long-lasting tennis balls have solid, rubber cores. Often called "pressureless", these balls are a good choice for people who play infrequently, as they do not lose their liveliness over time since there is no air inside them to escape. They do have to be replaced occasionally, however, since the felt will wear out. Penn tennis balls or Tretorn tennis balls are usually a good long lasting choice.

Numbers on the balls

Numbers on the tennis balls are right under the logo. This is so that when you have, say, 8 adjacent courts and some are using the same brand or type of ball, then there won't be a mix-up of someone's ball sprays onto the other court. Unless, of course, they're both using the same number tennis balls. For instance, if you are using Penn 3s, the court on your left has Penn 1s, and the court to your right has Wilson 3s, you can tell at a glance which court to throw the extra ball to and in turn they can get your lost ball to you easier.

Balls

If you are buying a whole mess of discount tennis balls from a tennis club or a friend -- just be careful. Heavyweight, dead, wet or any type of used tennis balls are heavier and therefore produce more force on the racquet. Fresh, regular duty balls are recommended.