5.88” 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. Boxed.