Pyrex Storage Deluxe 4-Piece Set with Lids Vented lids allow steam to escape while in the microwave Snap-on-the bottom lid prevents lids from being lost or misplaced and allows for compact cupboard nesting without glass to glass contact Footprint on the lid allows for easy stacking during refrigerator/freezer use Pyrex glass is safe in the oven, microwave, refrigerator, freezer, and dishwasher Made in the U.S.A.