Grab a 64-ounce or 40-ounce Hydro Flask water bottle for the lowest prices we have ever seen—even on Black Friday. Sign Up For Goods 🛍️ Product news, reviews, and must-have deals.

The Fernbach-style culture flask (invented around 1900) provides a larger liquid surface and hence a better oxygen transfer, albeit at the price of needing more space for the same amount of liquid.