Stove Jack Chimney Insert

I love the Overlandish products, however the stove pipe jack is about an inch too small to match the velcro on the window. I have the base camp 2.0. Maybe I was sent the insert for the solo? Or should I put it out in the sun light to make it more pliable? Using it for the AC exhaust since the 4" ports are too small. Again great tent. Any advice would be helpful. Thanks.