Visbella Stop Leak is a non-toxic compound for stopping radiator and cooling system leaks. It can quickly mix and flow into all areas of the cooling system to fix and seal leaks and permanent repairs for all Car,Truck, Van, Bus and Tractor Radiators. Powder is safe with all types of antifreeze and will not clog or harm your cooling system, but act as a rust inhibitor and lubricant to internal cooling system parts.