We designed the sleeve to fit tight enough that it won’t fall off, but loose enough that it is still easy to get on and off. Different brands and mouth sizes of jars will vary a little in size, but it should stretch to fit almost any of them.
Microwave safe means you can heat up your beverage without removing the sleeve. Or take out a frozen jar of food, put a koozie on it, and heat it up.
Since they don’t touch your beverage, I often just rinse them, but they are also dishwasher safe. You can leave them on the jar, but I find that water gets trapped so I prefer to separate them to clean the jar.
