To reduce the size of standard 24mm breast pump flange down to your size, if you're finding that you're not comfy or getting much milk when you pump. Flange size matters! A hard flange in the right size is generally your best option, but inserts can be really useful to find that size, or work with what you already have. Fits most 24-28mm flanges. Measure the tip of your nipple with a ruler or circular ruler, before pumping, and consider trying the exact size, 1mm up and 1mm down. And measure each side - nipples are sisters not twins! Available in 1mm increments from 11mm to 21mm. Each sold separately (make sure you add two if you need two!) Cleaning - wash before first use, sterilise if desired or with a vulnerable baby. After first use, clean with warm, soapy water. Rinse well and air dry. Please note that these will not fit well into the wearable Tiny Bloom Ivory or the Well care pumps as their standard flange is slightly larger.