The loops can be used to hang the entire duct on a rope or hook. This is particularly important with Layflat ducts.
The standard cuffs can be made longer, shorter and equipped with velcro or zipper as may be required.
These can be used to connect the duct to another duct, or a transition piece or velcro adapter. It can also be used to simply block the duct if equipped with ventilation holes.
Ventilation holes can be used to distribute hot or cold air as opposed to only transporting it from one end to another.