Silicone Food Covers The temperature tolerance of the silicone cover ranges from -40F to 446F approved dishwasher, freezer and microwave. Due to the good sealing,food covers allow bowls,cups or other containers to side lay or stack up for saving the space in a freezer. Bowl lids can used for covering the tableware needed to be heated in a microwave or oven. Note?You had better not completely seal container when you are using in Microwave or Oven.