Rash guards are commonly used in surfing when the weather is too warm for a wetsuit and to prevent wax-based chafing from sliding on and off the surf board, either on the chest or the legs. The wax on a surfboard traps sand from the shore, which can grind against a surfer's torso when paddling out to the break, creating discomfort. A rash guard provides some protection against this sand while still allowing a surfer to feel the water as he maneuvers his board through the waves. Surfers usually wear shorts under their rash guards; however, they may also wear swim trunks or jeans if the water is very warm or if they prefer. Wearing a rash guard comes with its own set of rules. For example, you cannot wear any articles of clothing underneath it that will show through at the material's hemline or sleeves. Also, you should choose a color that will not contrast greatly with the color of the ocean near your location. Finally, avoid wearing logos, since these will likely stand out when wet. Rash guards are commonly made of nylon or polyester and range in size from small (to fit under a shirt) to large (to be worn over a shirt). There are also knee-length versions available. Whether you're planning to surf cold waters or not, a rash guard is an easy way to protect yourself from sand while enjoying the beach.