Polo riders' equipment doesn't include which of these items?

Polo is a sport played on horseback, where two teams of four players use a mallet to hit the ball, with the objective of getting it through the goal. Each player has equipment for both gameplay purposes and safety.

To play the game of polo, the necessary equipment is a helmet, knee guards, boots, a saddle, and a mallet. One ball is required to play a match of polo. Each player rides a horse. However, horses are exchanged at the end of every period or chukka. Polo is a very fun and exciting game. However, it is quite dangerous, and the right equipment is needed to ensure safety for everyone involved.