I love, love, love these. I don't know why anyone would want to sit all hunched over, leaning forward while they pump...you can actually sit up straight with these. The sizing is different from Medela. It is more based on breast size than nipple size. I am a D or DD, and the large fits well in the pumpin' pals (I would use a medium in Medela). I can also use the medium pumpin' pals, but I don't get as much output. I initially bought the 3-pack to see which size fit the best, and then bought an extra set of the large to take to work with me. These are more comfortable because there is not a hard edge to rub against the breast. I use the Pumpease hands free bustier, and have always achieved a good seal/suction.