The 10” (25.4 cm) round duct system attaches to this duct collar plate. 26 1/8" 2 1/8" Ductwork Cutout Dimensions For Internal Blower Model Only! Countertop Cutout Dimensions For Both Internal and Remote Models WARNING! Product specifications are subject to change without notification. Consult the installation instructions for Rev. 07/11 both the remote blower and the ventilation system before you begin installing this rangehood.