All metal work is custom ordered and is made for each individuals specific application.  Arctic Marine Air does, however, offer standard metal work.   

Plenum: when ordering your plenum (the box that distributes the air flow) youcan order a remote series, which is located remote from the system.  The second is a Attached Series, which is attached directly to the blower (discharge) of your unit. 

Transitions: The transition is simply the part that allows you to attach the duct to the register. 

Duct Adapters:  The duct adapter is the piece that allows you to connect the duct to the blower (discharge).