Opticz 2 Ounce All Purpose Invisible Blue UV Blacklight Reactive Ink Invisible in regular light, glows bright blue in blacklight Choose between 4 sizes discounted by quantity. 2oz, 4oz, 8oz, and 16oz Ideal for glow parties, hand stamping, marking valuables, admissions, and much more! Safe and non toxic when used as directed Trusted Opticz Brand