This is at least of 4 pounds of nitrous oxide. Thisstuff is 99.9% pure and is used for making whipped cream.
This would be a crazy cheap price of only $10 a pound!
I cannot find what the empty weight of these tanks should be, but they are identical and one tank weighs a little more than 4 lbs. than the other. Assuming that one tank is completely empty, that would mean that the other tank would still have 4 lbs. of nitrous still in it. It's possible that the "empty" tank isn't quite empty, so there might actually be even more than 4 lbs here.
This product is marketed for making whip cream. If you even suggest that you might use it for anything else, I WILL NOT SELL IT TO YOU.
Price is $40 (cash only), pick up here in northwest Napa.