Squash balls are between 39.5 and 40.5 mm in diameter, and have a weight of 23 to 25 grams. They are made with two pieces of rubber compound, glued together to form a hollow sphere and buffed to a matte finish. Different balls are provided for varying temperature and atmospheric conditions and standards of play: more experienced players use slow balls that have less bounce than those used by less experienced players (slower balls tend to "die" in court corners, rather than "standing up" to allow easier shots). Depending on its specific rubber composition, a squash ball has the property that it bounces more at higher temperatures. Squash balls must be hit dozens of times to warm them up at the beginning of a session; cold squash balls have very little bounce. Small colored dots on the ball indicate its dynamic level (bounciness), and thus the standard of play for which it is suited.
Some ball manufacturers such as Dunlop use a different method of grading balls based on experience. They still have the equivalent dot rating, but are named to help choose a ball that is appropriate for one's skill level. The four different ball types are Intro (Blue dot, 140% of Pro bounce), Progress (Red dot, 120% of Pro bounce), Competition (single yellow dot, 110% of Pro bounce) and Pro (double yellow dot).
The "double-yellow dot" ball, introduced in 2000, is the competition standard, replacing the earlier "yellow-dot" ball. There is also an "orange dot" ball for use at high altitudes.