Elite Software announced the release of Manual D Ductsize (MDD), which is a fast and simple program used for sizing and analyzing HVAC duct systems based on ACCA's Manual D procedures. MDD analyzes both supply and return duct systems. A built-in fitting selector displays hundreds of ACCA duct fittings. Optimal duct sizes are calculated for both round and rectangular duct sizes and all types of duct materials are accounted for.  Even 2" high velocity duct systems can be sized accurately.