Glass is pre-heated oven safe up to 425 degrees F. Our tempered tough glass is also microwave, freezer, and dishwasher safe, and is up to 100% stronger than regular glass. True seal a glass food storage containers help protect the flavor of food and will not stain or absorb odor - they are also stackable and nestable for easy storage. True seal a lids are designed to prevent spills and leaks, and lock air out while sealing freshness in. Anchor Hocking glass is made in USA.