This is the most widely used, versatile, most aggressive, and popular cleaner we offer. It is the only cleaner of the four the manufacturer offers, that removes the most difficult debris including gums and tars. Although it is the most aggressive cleaner by far it is safe and gentile enough to use on manufacturer applied coated optics. A little goes a long way and it evaporates so quickly your lens or optics can be wiped dry or left to air dry. Unlike other cleaners that just move the dirt around, Lens Clens #1 actually extracts the dirt when a drop or two is put on a lens tissue, lens cloth, cotton ball or swab and applied to the lens in a circular rubbing motion from the inside or center of the lens to its outer edges. Because of its unique ability of Lens Clens #1 to remove all of the dirt and debris from optics more effectively than any other lens cleaner available satisfied users have told other users about the effectiveness of Lens Clens since 1971, and it has spread from industry to industry by work of mouth advertising only. We sell the most popular size bottle: 1.7oz/50ml bottle.