Take a look at similar Hi Gear tents and see if there is an extension available for them, then do some measuring of your own (usually the peripheral length of the arch over the last hoop is the critical dimension) on their display models to see if compatible with your tent. Friends found that extensions for a similar new Hi Gear tent would fit their now discontinued model, if fact they bought an extension, then a closed porch at different times by doing that. They now have a tent plus two extensions that is the size of Blackpool Tower ballroom! - fitted about 30 of us, all seated, in it once!