Advance HID ballasts are available to operate the wide variety of metal halide, high pressure sodium and low pressure sodium lamps available in today's marketplace. Like fluorescent, HID lamps are gas discharge lamps. Light is produced by an arc discharge between two electrodes located at opposite ends of an arc tube within the lamp's outer glass envelope. The ballast is the lamp's power supply; its purpose is to provide proper starting and operating voltage and current to initiate and sustain this arc. In addition, Advance now offers 120/208/240/277/480V 5-TAP core and coil ballasts for the most popular applications. 5-TAP ballasts add the 480V input lead to the Quadri-Volt designs. A Quadri-Volt or 5-TAP core and coil, along with the appropriate capacitor, ignitor (where required), mounting bracket and hardware and installation instructions are packed in a space-saving shipping carton. These "kits" eliminate the need for distributors or end-users to stock loose components of single voltage ballasts for 120, 208, 240, 277 and even some 480V applications, though single voltage kits for 480V applications will also be available.