Yes, you can use either sizes. I just thought 51mm was pointless when you have to reduce down again for the Superlight pole. Only my opinion mind, the pics show my system and i'm happy with it. If i wanted to improve it then maybe a straight inlet to the side or maybe hose that is smooth on the inside but niether would improve it dramatically. There is a more powerful vac about that would be even better, but for normal jobs this one seems fine.