PRODUCT DESCRIPTION: MASK NOT INCLUDED!  This fog wiper (Yellow Color) is a manual device that allows the user to slide a magnet/wiper on the outside of the lens, causing an inside magnet/wiper to move in unison and wipe off fog.  SIMPLE!  This product works with all types of firefighting airpacks (e.g. Scott).  Note that the unit price (quantity=1) is for one magnet/wiper on inside and one magnet/wiper on outside.  If your mask has two separate lenses, you must order TWO units (quantity = 2).  Available in three colors: Black, Blue, and Yellow.