Question about the Fluval AC20

If one of you lovely people that own a Fluval AC20 filter wouldn’t mind helping me out by pulling out a taper measure I would seriously appreciate it!

I am looking at the FLUVAL AC20 as a filter for my new tank. However I have a lid for this tank and would like to use it if I can. How much clearance does this filter need on the inside of the tank? I’ve looked into dimensions and have watched videos but I still can’t quite get an accurate perspective on this.

Just want to make sure it’ll be okay before I buy!

THANK YOU!