It is made of pantyhose and silica based cat sand. Works very well and is able to soak huge amounts of moisture. They are also very cheap to make. But, that aside, I took 8min and 2x4min exposures @ ISO100 just a moment ago without LENR. Now I have to say I am impressed with this little wonder - the photos have only like 10-20 bright spots which are easy to remove. And this is with 2 stop push!!! This is like better what K-1 does at similar times or about the same. I have never seen anything like this with APS-C camera. Now I am going to get the D-BG7 grip with K-1 battery to get more live view usage out of it.
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Here is the 8 minute one. No LENR, 1 stop push!
This is superb performance. I suspect there is some kind of spatial filtering method done to RAW file without asking the user anything but it works rather well. Not as aggressive as Sony "optimizations".