The Medela milk bags allow you to pump directly into the bag, but for other brands, you need to pump into a bottle first and then pour into the bag. Personally, I think the Medela bags are too expensive (> $6 per piece). I recommend Boots milk bag. You can get them at Baby Outlet ($68 for 40 bags). In Thailand Boots, it is so cheap, just 120 Baht. So if you have friends going there it will be good to ask them to buy for you.