Cardios gonna kill my gains.

Which part of the back is hot? Top or lower? or all?

https://www.amazon.com/dp/B07967ZH9K/?coliid=I2H8DO5VWIOL6G&colid=TW4MWDRFCNYG&psc=1&ref_=lv_ov_lig_dp_it

Would this breathe better you think?

I drink at least 3 Liters a day, more if I'm lifting. That's why I want the biggest bladder.