Go Green food storage containers employ the latest advances in nano silver technology, They'res infused with FDA-approved, nano-sized particles of silver that inhibit the growth of mold, fungus and bacteria, thereby allowing foods to stay fresher longer than in conventional plastic food storage containers. Go Green containers are BPA free and are microwave safe without the lid. They're also safe in the freezer and on the top rack of your dishwasher. The lids are airtight and watertight, with a soft, flexible silicone seal. Go Green containers are the lightweight, unbreakable, airtight, containers for safely storing and transporting all your leftovers.