In item description "Improving sealability by packing packing in upper pig". The actual thing only has a sponge sheet stuck on the lid. There is no doubt that the sealability has improved rather than nothing, but it is impossible to sing it as airtight. And why only things that stuck the sponge are so high ...? I bought this product because I wanted a brush box that could be placed in the car without worrying about solvent odor and liquid leakage, but it is too much too lame. I was disappointed very much.