Forward curved, airfoil and inline fan discharge are dust collar w/1" flange.
Plenum bell and direct drive fan discharge are outside section opening including face flange

MULTIZONE
Horizontal Discharge - 2 deck multizone available sizes 030 - 330 only
Vertical Discharge - 2 deck multizone available sizes 030 - 330 only
Horizontal Discharge - 3 deck multizone available sizes 030 - 190 only
Vertical Discharge - 2 deck multizone available sizes 030 - 190 only

*Outside dimensions include mounting flanges (face) type