Yet another first for Onyx! They have designed and manufactured the very first stainless steel ice pack. 100% non toxic! The body is made of 18/8 stainless steel, and it is filled with distilled water. So it is safe to go right into your container, next to your food. This is the small version, meant for keeping your lunch fresh. It freezes solid in about 2 hours, and will keep your lunch cool for 4-6 hours, depending on your containers and your lunch bag. (just like any other ice pack)?