The SATCO T9 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 S6506 T9 circline fluorescent lamp is designed to provide energy savings in slim spaces. The 40-Watt, 4100K cool white lamp fits into circular fixtures with four-pin bases. This Circline lamp can be used in both decorative and retail environments.