Perman UV Ultra Violet 21 LED 395 nM Flashlight Mini Blacklight Aluminum Torch Light Lamp Emitted Purple for CSI Inspection Ligh 21 LED UV 395-400 nm flashlight. Emitted color: purple. Long service life. Light weight. Aluminum. shockproof. Suitable for outdoor activities as well. Powered by 3 x AAA alkaline batteries (not included) (work time:more than 20 hours) Great for checking notes, credit cards, fluorescent inks (invisible inks), cracked glassware, or even crime scene. Note:Due to the intensity of this UV LED device, UV protective glasses are recommended. DO NOT look into this device while operating and DO NOT shine in any person's eyes.