Bests & Worsts Reviews from Amazon

I have bought blocks like this is past from amazon, and they were underweight. 9 pounds for 1 block and 9.8 for another. I bought 3 of these on this order, and ALL of them weigh 10 pound each, EXACTLY 10 pounds each. I cannot see how it is advertised as 11 pounbd blocks when they are underweight. It's a bit nit-picky, but in total order, I was 3 pounds underweight. That may not seem like much, but when you realize that 250g = 1 gallon plant pot after coco is expanded, this means I am short 12 gallons of expanded coco coir. I grow in 3 gallon pots, so 4 pots are empty. :( Amazon fulfilled the order, so they should realize they are short changing customers on this item.