Rated 3 out of 5 stars

This is a helpful feuture, to make it much better i would like to see a dropdown with template widths. Ipad, Ipone, 800, 1200 etc.

This review is for a previous version of the add-on (1.2). 

Thank you for your review! The simple reason to why there isn't a list of pre-defined devices is that there simple are too many devices to cover them all. I felt that either I had to include all of them or none of them. But if you would find it useful with a list of template widths there are a lot of other extensions that does this already (for example: https://addons.mozilla.org/en-US/firefox/addon/firesizer/).