A lot of pro uniforms are made of some kind of light-weight synthetic fabric now. It is cooler and air circulates through it.
I bought an “authentic” jersey from the AA team that plays near here, and when I got it I was like: “what kind of cr@p ios this?” and was told “this is what they are wearing now, and the players like it better.”
WalMart employees wear vests that they LOVE. It keeps them cool.
It’s re-cycled plastic