Looking for a value driven, alternative solution to your name brand "factory" replacement lamp? US Water Filters replacement lamps are made to the exact same stringent manufacturing protocols, and are backed by a one-year, no-hassle warranty. The USWF-140113 is a replacement for the VIQUA 602807 ultraviolet lamp, for use in the VIQUA F4, F4+, F4-V, F4-V+, F4-50+ systems and the discontinued Trojan PRO15 system. Easy to install and maintain with replacement needed every 13 months. After 10,000 hours the UV light weakens and isn't strong enough to properly treat your water. Replacing your lamp annually ensures optimal system performance. Safety Note: NEVER look directly at the UV lamp when it is powered on. Follow the instructions carefully to avoid injury to eyes and skin. After a year, UV light weakens and isn't strong enough to properly treat your water. Replacing your lamp annually ensures optimal system performance. Includes 2 replacement o-rings.