It does work, it's great. The only thing is the sizing. I got a 2XL and it's pretty tight if you've got a couple of layers underneath, usually for me that's like a baselayer (Uniqlo Heat Tech) and a sweatshirt or something. Could do with a couple of sizes bigger. They're all made in China so definitely size up.
I think it was by Energy Vest. It's this one promoted by Gary Neville (?) anyway. Google doesn't show any results though.
https://youtu.be/Qd2bYxrK6yk?si=xuBwU9kDu6nrqZk6
It does work, it's great. The only thing is the sizing. I got a 2XL and it's pretty tight if you've got a couple of layers underneath, usually for me that's like a baselayer (Uniqlo Heat Tech) and a sweatshirt or something. Could do with a couple of sizes bigger. They're all made in China so definitely size up.