Clean Water Systems C4, C4A, C4B, C4BA, CR3 Crystal Clear Martin Water CUV7 Crystal Clear Martin Water CUV7E Glasco 1842 Eiko G10T5L Ideal Horizons 2001, 12001 Siemens LP4165 Sunlight LP4165 Ultra Dynamics 7008-248, DW300 G10T5 1/2L The lamp is 17 watts, 357 mm in length and has a single pin on both ends, rated effective life 10,000 hrs., change once a year.