Currently we have GTM setup to record all impressions and clicks on the advertisements on our website which then records them into Google analytics. Our problem comes in because we have advertisements that display only on screensizes less than 400px but our impression tag is calculating the mobile impressions on desktop browsers.

The idea we have is to setup a new google tag for impressions for the mobile only ads and have them trigger when the screen size is less than 400 otherwise the impression for desktop fires.

I had this all setup a while back and need some assistance piecing all this together. Any help would be appreciated!

Current Desktop Impression via the previewer

I tried creating an additional variable called “screen resolution” with custom javascript (screenshot attached). Now I am stuck.