The average adult needs two liters or quarts of water per day (64 ounces). We like these small pouches because they are incredibly durable, and the 4.25oz size means that if one gets spilled your entire supply is not lost.
The extra .25 ounces allows for "practical uses" like washing and cooking.
They look and feel like juice pouches (without the little straw).
Pro Tip: Water doesn't expire - manufacturers put age limits on everything, but these can last indefinitely as long as the foil packaging isn't damaged.