A. Negative Pressure: Yes - No - Unknown B. Operating Voltage, Phase and Frequency: Volts . . . . Phase . . . . Hertz (60 Hz Standard) C. Door Type: Single Hinged - Double Hinged - Sliding - Roll-up - Return Track- Vertical Lift - Garage Style Other: D. Number of independent moving doors the air curtain is mounted over: ONE - TWO (i.e. double-hinged)