Cal-Blue Plus is a complete gas leak detector with freeze protection to 5˚F. Its high viscosity formula enables it to remain in contact with the applied surface for an extended period of time, allowing it to detect the smallest of leaks. The longest lasting bubbles in the industry! It is also non-corrosive to metal, and it will not affect ultraviolet or black lights. Now available in a non-aerosol pressurized container that can be sprayed at any angle! NSF registered.