Nextorch Dr. K3 UV Pen Light DR. K3 UV5. 88" overall. Clip. Water resistant. Impact resistant. Tailcap switch. 365 nm UV LED. Detects cat ringworm, skin abnormalities, FWAs (Fluorescent Whitening Agents), and Counterfeit bills. Wood's lamp is a kind of UV light that works at a special wavelength. Some microorganisms and natural chemicals will show specific colors under its light. 1 hour, 15 minute max runtime. Requires (2) AAA batteries (not included). Aluminum construction. Color: Black.