Krytox™ GPL 155 oil and GPL 255 grease are special products with fluorescing agents in them to allow the use of a black light to determine the uniformity of an application. They are not intended for routine application as lubricants without qualification testing. The fluorescing additive is present at low levels, but its effect on lubrication performance has not been tested. Under ultraviolet light, the products give off yellowish-green color that is visible to the unaided eye. The only equipment necessary is a standard broad spectrum ultraviolet lamp, commonly known as a "black light."