A side box for a bike is a storage compartment that is typically mounted on one or both sides of the motorcycle. It provides additional space to carry personal items, such as a change of clothes, a laptop, or other belongings. Side boxes come in various shapes and sizes, and can be made of different materials, such as plastic, aluminum, or fiberglass. They can be locked for security and often have weatherproof seals to protect the contents from rain and other elements. Some side boxes can be easily removed or attached to the bike, while others are designed to be more permanently fixed in place.