Well I'm trying to get hold of some of the 'new' ungenuine 30k attys from a supplier who has stock they now cannot sell because of the bad press, with the 901 whistletips the only problem with them (not fitting onto the cart snugly) is solved as the 901 carts seem ever so slightly bigger. There is a definite variance though, some fit my Joye atomisers perfectly and some are extremely tight.