The lid of Glass Storage Containers have a sealing air hole, gently press the yellow button to release hot or cold air, press it again can be sealed completely, now you can easily put any food, have a nice meal! [Oven,Microwave(Not the lids),Dishwasher Safe /Freezer Safe] These containers are oven safe below 752H, you can use them for freezer storage,microwave(not the lids)and dishwasher. Easy to use and easy to clean.It's safe to wash the lids in the dishwasher, but high temperatures over a long period of time can deform the silicone sealing strip at the edge of the lid. Please wash the lids by hand as much as possible. [BPA Free] Glass Storage Containers are BPA Free, which will maintain the freshness and keep your food odorless.It's made out of borosilicate glass for easy heating and durability. And in order to prevent the rubber seal sticking to the glass containers, please must wash the lids and glass containers before put them away.