This Precision Lighting 285-D2 18 watt bottom screw down CFL socket adheres to the strictest quality control and quality assurance procedures in the ballast and lamp industry. This CFL mount is for use with 2-pin G24d-2 and GX24d-2 bases. Each Precision Lighting product is tested under the toughest conditions and meticulously factory checked for defects in materials to reach you in perfect condition.