Spectra Compatible (Maymom) Wide Neck Breast Shield for Spectra S1 / S2, Synergy Gold & Compact and 9Plus Pumps

Hello!
My recent purchase included 2 flanges for spectra breastpump.Which one of them, 21mm is with defect, and that most likely affect suction.

Materials are durable, easy to clean and to fit. I have more concerns about the flange size. Before submitting my order, I have printed the chart guide in order to choose the correct size for me. This model has a kind of ruler to cut, easy to understand. I have ordered the 21 cm because my nipple is 18cm but I have developped soreness and nipple blebs after using because the flange is too big.