I forsee a lot of these left alongside the highway as drivers shred them from going too fast with them on...
They cost around $700 for six of them as they're sold by the pair for around $235. IF you don't drive 'em on bare roads and keep speed to a max of 25mph they should last many years. Drive to fast or on bare pavement and they'll be ruined almost immediately. For "max chain", you them on all four outside drive tires (locking the link between the the shafts) and on the two rear outer tandem wheels. You can't really put them on the inside drive tires