The SATCO T5 circline fluorescent lamps are designed to provide energy savings in slim spaces. These lamps are designed to fit into circular fixtures with four-pin bases. Circline lamps can be used in both decorative and retail environments.|The SATCO S8155 T5 circline fluorescent lamp is designed to provide energy savings in slim spaces. The 40-Watt, 3500K neutral white lamp fits into circular fixtures with four-pin bases. This Circline lamp can be used in both decorative and retail environments.