My objection with the MetalCloak design is twofold. First, they cripple the spring by intentionally collapsing the upper half of the coils: this effectively lowers the upper coil perch and creates a shorter spring - are they still actually advertising that as a benefit? - which is not only kind of counterproductive, but also has no practical advantage. They like to say that it helps to keep the spring from unseating, but designing a spring to keep itself from unseating makes very little sense when so many other methods are available that don't require a design change to the spring. My second objection to the design is the result of the collapsed upper coils: the lower coils have to do all the work...and there are only five of them. Phrased another way: they reduce the number of effective coils for no reason, to no benefit.