Cowboy polo is a variation of polo played mostly in the western United States. Like regular polo, it is played in chukkas (periods) with two teams on horses who use mallets to hit a ball through a goal. It differs from traditional polo in that five riders make up a team instead of four, western saddles and equipment are used, and the playing field is usually a simple rodeo arena or other enclosed dirt area, indoors or out. Also, instead of the small ball used in traditional polo, the players use a large red rubber medicine ball and use mallets with long fiberglass shafts and hard rubber heads.