Coolshirt Maintenance Additive was developed by Coolshirt technicians as the best way to keep Coolshirt driver cooling systems clean and and tubing in your car and your garments clear of mold, etc. The non-toxic, biodegradable solution contains a fungicide, yet it's safe to use in all Coolshirt cooling systems. Regular use of Coolshirt Maintenance Additive will not only help clean your system, but it will also improve the performance and life of the system pump. Use 2 oz. of additive every time your Cooling system is used (6 oz. for the large multi-person pit cooling systems).