I read elsewhere that TSER is the true value for measuring heat rejection and not the IRR.
I'm just curious how it applies to analysis of existing tints.

Using Sunbloc as example:
Carbon (low-tier) VLT36 has IRR 65.0 and TSER 54.0, while the Ultimate Ceramic (mid-tier) VLT37 has IRR 79.0 and TSER 53.0.

If we base our judgment on TSER, then it would seem as if the Carbon film is actually better than the Ultimate Ceramic? At least, for heat rejection, which is what most people are usually after. Why then go for the more expensive ultimate ceramic? Should the IRR still be a factor here?