Rather than downloading a potentially unsafe compressed file (like a .rar), ASHRAE provides several official, secure methods to access this data:
Older database versions (like 5.0) are sometimes integrated directly into design software like Autodesk Revit to help MEP engineers calculate pressure loss during the design process. Risks of Third-Party ".rar" Downloads Download ASHRAE Duct Fitting Database rar
A more comprehensive mobile version covers all 240+ fittings listed in the ASHRAE Handbook of Fundamentals and allows for project saving and report emailing. Rather than downloading a potentially unsafe compressed file