I bought these collection cups at the recommendation of a popular exclusive pumping page on Instagram to use with my Spectra. Overall I am really satisfied with the function of these cups. They remove milk better than I expected, and my supply has increased by about 5 oz a day overall since using these. They are easier to cover up if pumping in public or in the car. I discovered after purchasing these that I needed to size down from a 24 mm flange to a 21 mm. I ordered the Maymom inserts on Amazon for my Spectra flanges and also the 21 mm silicone flange that goes with these cups. Strangely the Maymom inserts in the 24 mm silicone flange remove milk better for me than the actual 21 mm silicone flange. I do find that occasionally I start getting a clog after using these, but I like the option of switching it up between the spectra flange and these cups.