The main unit uses PPF so it can be used for heating in the microwave. Resistant to heat, oil and shock. The rib shape allows air to escape during the range up. This allows you to use the microwave while the lid is closed without air holes on the top.

Product Name: Acorn Container, Black Transparent Lid Set (KDN175-350 Black Body + KDN175 Pie Serving Lid) Manufacturer: North Country of Origin: Applications: Various bowls, noodles, kowa, fried han, salad, deli food, etc.; Size: Main body outer dimensions: 7.0 x 7.0 x 1.6 inches (1777 x 1777 x 41 x 41 x 41 x 41 mm) / Lid external dimensions) Capacity: 350cc Material: Main body PPF / Lid OPs; Weight: Main unit 0.5 oz (13.7 g) / Lid 0.2 oz (6.5 g)