V-kool Elite rejects heat a little better than 3M crystalline 60/70 at the expense on GPS signal.
The old V-kool had problems with smart tag but it's ok with the newer ones.

Don't worry about the "metal rusting" cos on the 2 cars with v-kool in my house, one's been on for 8 years
and the other had been there for 5 yrs and they both look no different than when new.
Especially the 8yr car, hardly anyone cares for it, parked under the sun more often etc.

When I keep testing the difference (cos I keep feeling the 3M is not cool enough), the 3M still can feel
the burning sensation on hot days while the V-kool, although difference is not too big feels much better.