The Original Big Blu leak detector is trusted by OEMs and HVAC professionals worldwide and is the only bubble solution capable of detecting microleaks as small as 0.65 ounces per year. Its unique elastic formula clings to surfaces and produces long-lasting bubbles, helping technicians quickly pinpoint even the smallest leaks. Safe for use on all gases, including oxygen, Big Blu is non-corrosive, biodegradable, and NSF certified for use around food.