The Rockwell Collins NAV-4000 Navigation Receiver includes the VOR/localizer, glideslope, marker beacon and ADF receivers all in a single unit. The NAV-4000 provides radio navigation functions. The NAV-4500 is identical in size to the NAV-4000 but does not include the ADF receiver. The NAV-4000 is part of the Pro Line 21 CNS products that have digital signal processing technology, digital audio, a consolidated tuning/data/audio bus and software data loading. The purpose of the Pro line 21 navigation receivers is to support radio tuning and tuning from the Flight Management System. The ADF receiver and ADF-4000 provides the locations of the signal with respect to the aircraft body. The dimensions of NAV-4000 are 3.44 inches high, 2.50 inches wide, 14.11 inches long and weighs 3.4 pounds. The input power for the NAV-4000 is +28 VDC.The NAV-4000 provides the capability to determine direction to non-directional beacons or AM broadcast stations operating in the 190 to 1,799, 2,088 to 2,094, 2,179 to 2,185 kHz frequency ranges.