Sylvania DULUX T/E/IN/EOL ECO compact fluorescent lamps are up to four times more efficient than the incandescent lamps they replace. This exceptional optical performance is due to our triple tube delta configuration: three-twin tube T4 fluorescent tubes in a triangular pattern. All DULUX triple lamps employ a 4-pin base for use with the industry standard socket. The new 57W DULUX T/E/IN/EOL ECO lamp adds a base enhancement, designed to take advantage of the industry trend toward a twist-lock socket, which ensures positive and dependable base engagement. Also, the 57W DULUX T/E/IN/EOL ECO amalgam version delivers 4300 lumens, making it one of the most powerful multi-tube compact fluorescent lamps in the world.