Aroma fresh range just unlock the 4 clips and the vent will do the rest its all down to the one way valve which allows each box to vent steam when required but wont allow air in so splatters in your microwave become non existent the integrated seals mean therell be no food traps for extra kitchen hygiene we know youll appreciate and theyre all stackable to make the best use of space in the freezercapacity 21lset of 6 food storage containers