Mine arrived today, shipped standard first class - (shipped Friday, arrived Monday) thanks!
I use this kind of thing, slightly compressed across its width, in place of a Bio-Bag or similar on a whisper HOB filter. Works with other brands as well, of course. For just mechanical filtration, its a finer pore than the fiber of the bio-bag things, and provides more bacterial surface area, so a used one is great to put on a new tank to seed it. On larger HOB filter models, I'll put the frame that came with the filter in front of it, to keep it from bowing towards the outlet. By cutting it a bit larger than the frame of a bio-bag, the compression keeps it very well "sealed", too.
In terms of pore size, its finer than the block of foam in an Aquaclear HOB power filter.
I'm also going to try this wrapped around the center of an Aquaclear QuickFilter powerhead attachment, for "macro" mechanical filtering.
JUST what I was picturing - excellent!
-Jane
PS - Discusonly, I don't think these were made by an Aquarium Equipment company - in a PM, Todd said "These pieces were originally used for packing lithium ion batteries for shipping."