Handy Convert is released with two versions; Free and Pro. Both versions function the same however the Pro version adds additional conversion categories and units (with additional ones to be added in future updates). The free version essentially allows you to try before you buy. If you like the interface and functionality, please consider upgrading to the Pro version. However, if the free version suits your needs, please enjoy using it!
<Link to iTunes>
An upcoming update to Handy Convert Pro will add even more categories and units based on user feedback and ideas. Thanks for the suggestions and keep 'em coming!