Cal-Blue Plus is a complete gas leak detector. Not only does it detect the smallest leak, it also provides other significant features and benefits. Its high viscosity formula enables it to remain in contact with the applied surface for an extended period of time, thereby allowing the smallest of leaks to be detected. It is also non-corrosive to metal, and it will not affect ultraviolet or "black lights". Additionally, it is freeze-protected to 5°F and safe for use on most gases, including oxygen.