The Sterilight S330RL lamp is the low pressure regular intensity original replacement UV bulb for Sterilight S2Q-PA, S2Q-PA/2, S2Q, S2Q/2, S2Q-GOLD, S2Q-GOLD/2, SC4, SC4/2, SSM-17 water disinfection systems. When you buy a Genuine Sterilight S330RL UV lamp you can be assured of the performance, safety, and warranty of your system. These Sterilume-EX lamps can be used in Silver series, old style Gold Sterilight series and the 12V DC system only.