I am exclusively pumping for tiny twins in the NICU using a hospital-grade pump and am amazed at the difference this has made for me. My supply went up by about 50% when I started using the flexishields and pumping time halved. Yes, that extra nub of silicone is a puzzler but I am still very happy with the performance I get with this. I always start with the Flexishields then if my flow dwindles, pump for the last few minutes without it since the suction is much stronger. They are wonderful for me especially for getting the my let down started. I am very happy to have found these!