The ZwypConvert - Paid Edition adds conversion of Pressures (PSI, Inches of Mercury, Bars, etc.) to the already extensive list of ZwypConvert conversions.

In addition, the Settings window is available to change the decimal precision for the conversions in each of the conversion groups.  Along with precision you can also ask to have fractions rather than decimal numbers displayed.  For example, 1.5 gallons will display as 1 1/2 gallons.  Finally, the Settings window allows you to have the result specified as a number of lesser units.  In that case, 1.5 gallons will display as 1 gal 2 qt.

Finally, the ZwypConvert - Paid Edition removes the advertisements that appear on the results screen and from time-to-time on the full screen.