6" x 25 Ft. Fab 6-T Fabriflex Acoustical Duct, R8 (Insulated)

This duct's helix is a flat metal several time stronger than the big-box store alternatives. It does make it difficult to get it onto the boot/wye but in return it sags a lot less and wants to take the most direct route which is critical when reducing static pressure loss. If you pull the sleeving over the zipties and onto the wye, the duct will straighten out nicely. The inner core is a cotton-like material to reduce noise as best as possible without using an actual silencer.