Size of featured images on blog grid

Hi there,

I can’t figure out how to get the images on the blog grid to display with the same ratio as they do on the enfold demo. No matter what size I use for the featured image they seem to be cropped differently and therefore the blog grid doesn’t line up nicely. Is there a particular size I should use?

Here is the page that I’m talking about: http://tryzens.com/about-us/press-releases

Thanks

Charlotte