Because the Quantum Realm is cold.

Just ask Ant-Man -- he traverses seas of frigid atoms in order to break down the microscopic circuitry adorning especially tech-savvy malcontents.

So, Scott Lang complained an awful lot to Hank Pym regarding the apparent limitations of Ant-Man's already temperature-resilient super-suit

Hank -- after mumbling a few choice words that sounded like "weakling" and maybe "soft" -- eventually relented and granted Scott the Pym Tech Distressed Logo Men's Hoodie.

Treated with experimental Pym Particle bombardments, these Pym Tech men's hoodies feature drawstring ties, spacious pockets, and a head-warming hood.

Made from 55% cotton and 45% polyester -- and based on Marvel's series of Ant-Man films -- these fine Ant-Man hoodies also feature red, white, rectangular and distressed Pym Tech logos.

Sleeve-stamped graphic!

No, that's not a sizable red ant preparing to impale your shoulder -- it's part of another company logo adorning the sleeve.