I purchased 48 of these. I was at the end of my first box of 24 and had been consistently finding "duds" since the Liss cylinders were purchased. Even when I was able to produce whipped cream, the pressure would fizzle out halfway through the cream, and I would have to add another cylinder to finish it. At first I thought it was a defective cream whipper and suspected a leak. Finally after two unsuccessful attempts in a row to make whipped cream, I used a gram scale to weigh the cylinders. Out of a box of 24 NEW chargers 13 weighed less than 23g, 8 of them weighed 20g(the weight of an empty cylinder) and had no NO2 at all. The "full" ones only averaged 25g, so had an NO2 charge of only 5g not the 8g that is stated. Needless to say, I won't be buying this brand again.