Knee pads may be classified based on their application, such as sports knee pads, dancing knee pads, work knee pads, military knee pads, and so on. The usefulness and amount of protection provided by these knee pads vary. Knee pads can also be classified by type of material they are made from, such as leather, plastic, foam, gel, and rubber. There are two main types of knee pads: standard knee pads and full-length knee pads. Standard knee pads are thick pieces of padding attached to your leg with straps or elastic bands. They are useful for protecting specific areas of your knee, such as the inside or outside of your knee cap. Full-length knee pads cover the entire front of your knee. These pads are used to protect against more severe impacts to your knee that might otherwise cause it to buckle. Full-length knee pads are usually made of thicker materials than standard knee pads to provide better protection. Some people who play sports that require them to jump start a car often use a device called a jumper cable as a safety precaution. The cable consists of two wires, an orange and a black wire. The orange wire is connected to the battery while the black wire is connected to the body of the car.