The pads are available in a range of shapes and sizes. More padding is preferred by defensive players to protect them from high sticks, pucks, and severe physical contact. Offensive players use lighter pads, sacrificing protection for more flexibility and comfort. The top of each pad has a plastic cover that can be removed for washing. There are two types of football pads: defensive and offensive. Defensive players wear pads under their uniforms to protect themselves against other players' bodies; offensive players wear pads so they can tackle others out on the field. Both types of pads consist of a hard outer shell with flannel or nylon fabric inside the shell to provide warmth and moisture-wicking ability. The interior lining is usually cut slightly oversized so it can be fitted to the player's body. Leather straps and buckles hold the pads on the player's legs and arms. Each pad has several holes cut into it for ventilation. There should be at least one large hole in the center of each pad for water to drain away from the body. Players choose between heavy duty and ultra-lightweight pads depending on the type of game they will be playing. Heavy duty pads are thicker and less flexible than ultra-lightweight pads but they offer better protection. A protective cup may be worn underneath the ultra-lightweight pads to cushion any possible blows to the head.