Opticz Industrial Invisible Blue UV Blacklight Reactive Ink (2 Ounce Bottle) Invisible in regular light, glows bright blue in blacklight. Industrial use only.Not safe for skin. See Opticz brand ALL PURPOSE UV INK for hand stamping and skin use applications Choose between 4 sizes discounted by quantity. 2oz, 4oz, 8oz, and 16oz Ideal for invisible security marking purposes. Mark auto parts, retail items to verify authenticity with returns, or virtaully anything you want to track undectected! Safe and non toxic when used as directed. NOT for printers or tattoos! Trusted Opticz Brand. Made right here in the USA!