Generate Thumbnail URL

Hey,

I have set up a new thumbnail in the settings for Sitefinity 6.1 and applied the thumbnail type to my library. Now I need to figure out how to get Sitefinity to return the URL for that thumbnail in a module I built. I read the best way to do this is to use regex to convert this url:

localhost/.../myimage.jpg

to this:

localhost/.../myimage.tmb-featured.jpg

Is there a better way to achieve this result? The object in question is a ProductImage object.

Thanks