I honestly dont know. Might just be that they were machined a little tight and the Air pin is a little long. If the tank is screwed down tight, there is no leak. If you screw it in without a little buffer in the bottom(o-ring) the pin actuates too early and air comes out and pushes the tank o-ring out into the threads and cuts it. Ive got a ninja tank with 2 o-rings and I dont have any leaking problems, but I get a top o-ring cut all the time.