Hensel UV Coated Flashtube for Integra 250, 500 Monolights UV Coated - has a yellow appearance UV Coated - Counteract the excess blue 5700 or higher output of non-UV coated flashtubes Flash tube can last for thousands of flashes before fusing out High Quality Flash Tube; For Integra 250 & 500 Monolights Note: This product may contain mercury.