Looks like a round sinnet to me, and from the looks of it the seller has removed the 'guts' from the paracord.
I brought this topic up on Plainsmans Cabin after trying to remember how guys made these in my Army days. A great 'how-to' was posted with pictures and everything. I ended up making a couple of the square sinnets, and haven't tried the round sinnet yet. All in all, they turned out fairly well.
If you want to take a like at that how-to posted on the Cabin, it's here:
SinnetJust a word, go easy on the bandwidth over there at the Cabin. Maybe someone could repost that entire how-to on ETS?