Air conduct fail

[CalMag]

Hello everybody, i need some help here.

I've got a 240x120x200 growbox with 2 exit for the extractors And 2 exit for the intake. All the four holes are 25cm sized.

I' have filter, extractors, intake that are 25cm but i have two reflector that are boxed like a cooltube but theese are coolbox.

Theese coolboxes are 15cm sized And i don't know how to fix the problem. I will use an extractor with conduction fixed to the coolboxes And fixed to one of the intakes hole (a standalone circuit).

Sorry for my bad english, thanks everyone!!

 

[Mikell]

You're looking for a round rigid duct reducer. I believe.

 

[CalMag]

Thanks, the problem is resolved by building a growbox And make the holes with the sizes that i need