I own a 510 and have used 510 and 901 carts. Oddly enough, the 901 carts do seem to draw easier. People also started using them on 510s when the "newer" atties came out because of a slight difference in diameter (used 510 carts were leaking with them). To my knowledge, you can't get the newer atties anymore anyway. Apparently they weren't official Joye products and for whatever reasons, people complained. Personally,I don't have a problem with them. To each their own......