I recently used 16 Oz to clean my exterior windows which had sprinkler spray calcify them pretty bad. Windex would not cut through the build up of the hard water, but Edfred's did the trick! Your product is a miracle in a bottle and I will be giving a gallon each to my parents and in laws for Christmas :). You have a great product, I just wish you had a better supply chain as Ace locally did not carry it and OSH was sold out last time I drove the 15 miles to get some. Have a good holiday and thanks again for such a great product which does what it says, which is sure rare these days