Galvanized metal can rust at the cutout edges. Paired with a straw, they are perfect for everyday use or for parties or weddings! You can choose to use them with any size Mason jar that has a regular mouth. Half pint jars are great for kids or for cocktails, and pint or quart jars are perfect for water, soda, juice, iced tea, or whatever you feel like sipping on. The hole is large so any of our straw options would work. Hand wash and dry. Fits any regular mouth Mason jar.