You need a non-invasive system of tracking human traffic in and out of your venue or event. UV Gear skin inks are the perfect solution.
As used nationwide by HMPS (Her Majesty's Prison Service).
Completely invisible on the skin, the inks can be applied by marker pen, roll on bottle or by an inking stamp. Fast drying and wash resistant. All skin marking products from UV Gear come with a handy "how to use" information sheet.