NOT polarized. 100% UV protection. CA has no tax.
Info taken from an Amazon reviewer JohnRon:
ByJohnRon November 26, 2016
The "Si" stands for standard issue as these are issued by various US government and military departments. These are the same as non-si Flak Jackets minus the "Oakley" logo across the nose bridge -- perfect if you're like me and prefer a more "stealth" look. Comes with a nice case, bag, and 2 pairs of differently sized nose pieces to customize the fit.