Ratchet straps, also called tie-down straps, are highly helpful when transporting cargo in a vehicle. The ratchets allow you to make sure the ratchet straps are taut and the items are tied down securely to a roof rack, truck bed or elsewhere. An S-hook lies in the same plane as the strap. This means that, depending on your application, an S-Hook might cause the strap to have a twist when it is attached.