Heavy-Duty Leak Detection Fluid Concentrate makes one gallon, just add water HD-LDF-C is a concentrate. Each 16 fl oz bottle makes one gallon of high tech leak detection fluid High viscosity resists flow for long contact time on vertical surfaces. Lasts longer. Extremely thin film makes it easy to detect small gas leaks. Works better Do you use Snoop liquid gas leak detection fluid? HD-LDF is half the cost of Snoop and works better