GKM9W Internal UV Spare Bulb. Sealed UV bulb design - avoid UV housing deteriorate, fresh with every bulb change. NO TOOLS REQUIRED! No gloves-No mess-EZ bulb changes! No Guessing – Control Box LED tells you when to change bulbs! Once your water is clear, there is no need to keep your GKM UV System ON 24/7. This will help increase the life of your 9 Watt UV lamp. EPA Est # 093568