there's also a filter pocket in here, again, for a piece of paper towel or better still, specialist nano fiber. super breathable, put it in your shoulder pocket and it works nicely. that's a great choice for a comfortable mask, you can wear all day, you can wash it. that works really well. some other options? >> i would love to. just from best to worst, or if you want to start from worst and go up to the best. >> so we started at worst there and then so this one, which is a cloth mask with the pocket and a wire at the top is a good choice. for the wire at the top, you can use rolled up aluminum foil, garden ties, whatever. this one has a garden tie, as you can see. >> okay. >> we have about one minute left. >> okay. >> speed demonstration. >> the masks, one of my favorite is called the nano mask which they've actually, they provide nano material with the mask, with some velcro and it holds his shape very nicely. but maybe to get. >> 95 standard in china, but it's not quite as carefully regulated. a key difference is the n-95, and the material. is that right, the key material to avoid is the st