Made Here Leak Detector Blue detects leaks in natural gas, refrigeration gas, nitrogen, air, CO2. Finds Micro leaks fast. Bubbles grow large and plentiful, lasting for hours. Leak Detector Blue is perfect for all types and sizes of leaks, even the smallest micro leaks. Its blue color makes the leak easy to see under a fluorescent light. Leak Detector Blue will not freeze and is perfectly formulated for both high and low temperature applications and for all types and sizes of leaks. Leak Detector Blue is environmentally safe, non-toxic and non-corrosive