HELP WITH TENt VENTS

Ok Roll it up, I finally after alot of research got together all my gear and will be starting a journal later today. But i need help in 1 area. I have a 250mm odour shock attached to a 250mm centerfugal fan. Now somehow i need to attach the 250mm duct to a 150mm sock attached to the side of the tent.

DIY is what im looking for but if i need to order a piece i guess i can wait another week before getting things up and running.

you need a ducting reducer, maybe 2. I know you can get a 250mm to 200mm and a 200mm to 150mm reducer