Honestly, who saves a beer unless it’s maybe a 15 liter bottle or something. I open a beer, I’ll drink it. This is how beer drinking works. Done! I got nothing to add to this!
From their product page:
Beer Savers are the world’s first durable, stretchy silicone beer bottle cap charms designed to help keep beer fresh after opening. They make a great gift for any beer lover. Home brewers can keep their beer bottles clean and sterile before bottling with these caps.
Buy it here: Beer Saver Cap