Firefox on a mac, "open with" d/l window.

I recently downloaded unzipping programs called theunarchiever and betterzip. Now whenever I go click on a zip file link I get the choice of open with stuffit expander or save as.

Now my question is when I click on the drop down window of open with the only choice is still stuffit expander i.e. BOMarchievehelper.app. Is there a way to let my open with drop down window include other than stuffit expander cause I have no use of it. Do I have to reinstall firefox or something?

I know that, I don't have stuffit expander installed but in the drop down list it has Stuffit Expander as the default program to open zip files.