21mm flange kit. 
FluidFit® breast shields feature a liquid silicone technology that mimics baby suckling - which can help promote milk flow, reduce nipple inflammation, and provide a more comfortable pumping experience. ‌The main body of this flange consists of the liquid silicone cushion that sits in a hard plastic housing. The cushion is suspended in the plastic housing and allows the nipple to be gently squeezed, or hugged, during pumping, rather than the typical pull-and-release that we see with traditional pump flanges. This hugging motion is how we get that ‘baby nursing’ experience. ‌Pumping can do a number on our nipple and areolar tissue. Using properly fitted breast shields is a critical component in preventing friction, pain, or even injury to our breasts. With traditional flanges, we want to add 1-3 mm to our pre-pump nipple measurement (how much we will add to get our flange size will depend on our level of elasticity) so that we have enough space for the nipple to move freely during that pull-and-release motion.With our Fluid Fit® Breast Shields we instead want to be using exact sizing, or within 1 mm in either direction. This is to allow for that hugging motion to occur and not have that pull-and-release motion take place. Because the cushion is suspended in the plastic housing, the nipple can expand outward a bit if needed so the exact sizing isn’t an issue as they can gently mold to your nipple shape and size. ‌It can take some time to adjust to new flanges whether that is a new size or a new style, so give it some time to see if these flanges are a better fit for you over the hard plastic of yesterday!