Material: Bread making proofing box is made of aluminum film and soft material. The 3 layer thickened design can retain heat for a long time and is durable. Portable: Sourdough starter warmer with handle, easy to move and take, convenient to carry. With Heating Mat: Warming mat, no odor, will not affect the taste of food during proofing. Hot and Cold Insulation: Sourdough ball proofing containers can keep warm for 4-6 hours and cold for 12-15 hours. Widely Used: Multifunctional pizza proofing bin can be used for various foods such as bread, yogurt, chocolate, pizza, etc., bringing great convenience to your life. Size Chart: 20L: 30cmx30cmx20cm/11.81inchx11.81inchx7.87inch 30L:30cmx30cmx30cm/11.81inchx11.81inchx11.81inch 35L:40cmx40cmx20cm/15.75inchx15.75inchx7.87inch 50L:40cmx40cmx30cm/15.75inchx15.75inchx11.81inch Package Includes: 1 Bread Making Proofing Box