Lamp holder has 4-Inch spacing between center. Lamp holder has anodized aluminum reflector that directs light away from vertical surfaces and onto your illuminated area. It snaps directly onto 9435 track and easily cut track to desired length. Lamp holder has voltage rating of 12 Volts. It is ideally used in hard to reach applications or in tight spaces. Lamp holder is C-UL-US and cETL listed.