Poor face seal is poor protection. Over 90% of 1500 tests of N95 masks failed due to users unaware of the leaks, According to a published study by Tongji Medical College, which conducted 1500 tests with 500 N95 masks on 50 Chinese.
To help identify any leaks, we developed the "water-mark" method; the frost internal surface of the mask turns into transparent when it touches wet skin. The transparent water-mark makes it easy to identify any gaps between the mask and the user's face. With Totobobo patented technology, ensuring protection and face seal is easy and accurate. 

 Is the mask too big for your kid? No worry, trim the mask to fit smaller kids (some cases down to 3 years old). 

You can even "test trim" with the "paper simulator". 

 Not getting a good seal? No problem, let's warm it up with a hair dryer or hot water to ReShape the mask to make it fit better!