A coolant recovery system is just a clear plastic container with two little hoses coming out of the cap. One hose leads to the radiator, and the other serves as an overflow pipe for the container. The container holds an extra supply of water and coolant, in case the system loses any.
When your cooling system heats up and starts to overflow, the liquid pours back into the recovery container instead of pouring out of the radiator overflow pipe and onto the ground. When the system cools off, the pressure drops and the liquid is drawn out of the container and back into the radiator. This process not only saves you coolant, but it also protects animals and children from sampling puddles of the toxic stuff.
Practically all cars made within the last 20 years have a closed cooling system (coolant recovery system). If you have an older vehicle/street rod/classic car and need to add a coolant recovery tank (also called a coolant reservoir) you can purchase one at Auto Parts Place. An online store offers discount car parts and auto parts for domestic and import vehicles as well as car accessories.