These are cast sections that very in length from 5' to 25'6" and along with additional extension sections you cut to length and add the transition end sections. You get 2 lengths 25' 6 " long ( 3 - 8'6" segments ) and 4 transition end sections. These pieces were designed to fit the standard roof for the Wide body cross section Extensions may be added to the increase the length. Choose the size you want from the drop down menu for DM 330A.
DM 330 HW AC duct work sections Starter set