Your opinion on KKCOBVR O2 head strap with battery?

I want to purchase this: https://kkcobvr.com/products/kkcobvr-battery-pack-head-strap-with-10000mah-compatible-with-meta-quest-pro-accessories-charging-dock-increase-the-use-time-by-2-3h-1

Does anyone have experience using this?