This Precision Lighting LK530-1 recessed double contact plunger lampholder is for use with T8 and T12 high output and very high output lamps and is rated for 660 watts. With an R17d socket, this 600 volt Precision Lighting lampholder adheres to the strictest quality control and quality assurance procedures in the ballast and lamp industry. Each Precision Lighting product is tested under the toughest conditions and meticulously factory checked for defects in materials to reach you in perfect condition.