The NAV-4000/4500, ADF-4000 and VIR-4000 are members of the Pro Line 21 CNS family of products that feature state-of-the-art digital signal processing technology, digital audio, a consolidated tuning/data/audio bus, comprehensive maintenance software and software data loading. The Pro Line 21 CNS products set new standards for size, weight and power in the business and regional aircraft market. They retain the same form factor as the current Pro Line II and Pro Line 4 products but have reduced widths that allow size reductions of up to 70 percent and weight reductions of up to 55 percent. These products also are designed and tested to meet the more stringent DO-160D Change 1 environmental requirements for helicopters and composite body aircraft.