Power Bank HELP

So I was trying to get a power back so that my quest doesn't die so fast anymore when I'm paying. I wanted to get something like this video https://youtu.be/XogAnuOcSjw?si=JomgOJV-pCYjfGfT But I'm the us amazon list that power back as only 15w.

What power banks should I look at or would be recommended here? I just wanted something simple and relatively cheap. I liked how he was able to just stick this one to the stock head strap without additional stuff needed. Thanks for any recommendations