These daisy lids are made of 304 grade stainless steel, so they won’t rust with normal use. The regular mouth center hole is 7.3mm, and an 8mm straw can fit through a petal. The wide mouth center hole is 10mm. You can choose to use them with any size Mason jar. 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. Paired with a straw, they are perfect for everyday use or for parties or weddings! They also make great lids for candles, potpourri, and other crafts. Dishwasher safe.