2.1 The Ball (Rule 3, FIVB Official Volleyball Rules 2025–2028)

All balls used in a match must have the same characteristics regarding circumference, weight, pressure, type, and color (Rule 3.3). In FIVB World and Official Competitions, three balls are used.

Source: Rule 3.1, Rule 3.3, Rule 3.4

Send this to your friend — argument over.