Copper washer is a type of flat washer made from copper, which is a soft and malleable metal with excellent thermal and electrical conductivity. Copper washers are typically used to create a seal between two mating surfaces, such as between a bolt and a nut or between a pipe and a fitting. When compressed, the copper washer forms a tight seal that prevents leaks and provides a secure connection. Copper washers are commonly used in plumbing and automotive applications, as well as in electrical and electronic systems. Copper is a good conductor of electricity and heat, making copper washers ideal for applications where electrical conductivity or thermal dissipation is important. Copper washers are also resistant to corrosion, which makes them ideal for use in outdoor or harsh environments.