"This kit features a high output 5 1/4"" long filtered ultraviolet longwave blacklight tube. Light up posters, invisible inks, many minerals, glow in the dark stars, products, etc. Completely portable as it operates on either a 6V lantern battery or 4D cell batteries (Batteries and battery holders not included). The output is filtered and it emits very little regular light spectrum. The deep purple glow can even be used to find certain insects, which glow brightly under UV light. Size of PC board: 5 13/16"" x 2 3/8"". Complete with all parts, PC board, tube and instructions. Skill Level 2."