This Nu-Calgon 4182-24 Cal-Blue Plus micro leak detector is a must-have for technicians servicing refrigeration equipment! This product is designed with a high-viscosity formula that makes detecting refrigerant, natural gas, and oxygen leaks as quick and easy as possible. Even small leaks are easy to find because Cal-Blue Plus is engineered to stay on the surface longer, and the bubbles produced when a leak is present will stay around longer than comparable products. It is safe for use on metal, and it will not interfere with ultraviolet and blacklight detection methods. It is freeze-safe to 5 degrees Fahrenheit, and can be used at temperatures up to 225 degrees Fahrenheit, too. The 1 qt. spray bottle makes it easy to apply the product with no dilution or preparation required.