The JDSU 1U-high power supply shelf contains two 330 W flat-profile power conversion cassettes that generate -48 V output. Each AC-DC unit is cooled by two internal fans and an alarm circuit, with Form C contacts, monitors the output voltage of each card. Mounting options include 19" or 23", via reversible ears, and ETSI. The unit features front-accessible air filters with airflow direction from front to back.