Heavy duty plastic. Very sturdy material. I love that they are lined.

Was supposed to be gray lining. They're a nice size so i’m keeping them, but they definitely slip around.

The thawmax is well constructed and easy to clean. Ditto for anything thick. The packaging is nice too. I love what it does for me on busy workdays.

Red rim stops excess water or juice from running off onto countertop. Also great feature is it is dishwasher safe! Defrosting trays are so heavily favored and have become the most widespread thawing method in the kitchen.