Ultra violet clues are a neat way to create interesting night caches. The general idea is that you create a clue that is only visible under UV light. We offer pens, paints and monofilament to help you create the clues for your cache. We also offer a variety of UV lights that you can use to discover UV clues in caches you find. We know of one cacher that purchased special UV inks for an inkjet printed and created a series of clues that respond well to UV light. Our 3-in-1 flashlights are our most popular. The laser comes in handy for pointing to a cache your friends are still looking for.