Image size

The plugin CSS for the images gives a max-width of 150px. Try overriding that in your theme with this:

#isa-related-downloads img {
    width: 161px;
    max-width: 100%;
}

You should generally leave the height set to auto, see if that looks okay. If you must, you can add to the above:
height: 101px;

Hope this helps.

No its not working, it always gives 150px, i have tried this before thats why I came here to ask help :(.

May be its my theme, i am using the new theme from EDD – Shop Front.

If you could please post a link to your site (that’s using the plugin), I could take a look at the source. There is, most likely, some other stylesheet overriding your
max-width: 100%;
If you post a link here, I’ll see what’s overriding it.

Apologies! Your theme’s CSS loads before the plugin’s CSS.
To override it from your theme, you have to use !important, although it’s not a “best practice”. You could add !important like this:

#isa-related-downloads img {
    width: 161px;
    max-width: 100% !important;
}

That will make sure your CSS overrides the plugin’s CSS.