Not all Medela pumps are open system pumps.

JuneBug86

I keep hearing this a lot between here, and a few other forums I am on. A lot of people think that all Medela pumps are open system pumps... not true! The freestyle, and the new Swing Maxi (it's the Swing, but in a double) are closed pumps. 

My guess is that they are slowly changing over to closed pumps for everything seeing how it is becoming more common knowledge that they are open systems. I'm betting in a few years they will all be closed systems or else they will loose a lot of customers. 

ETA:  http://www.medela.com/IW/en/breastfeeding/products/pumping/freestyle/media-seperation.html