The Medela PersonalFit Breast Shields, Small, 21 mm, were created in ranges to meet every mom's needs, because one size does not fit all. Manufactured by Medela, who is dedicated to breastfeeding moms and breastmilk for babies, the Medela PersonalFit Breast Shields, Small, 21 mm, are made without the use of BPA and are the perfect choice for women deciding to breastfeed their baby. For the ease of using Medela PersonalFit Breast Shields, Small, 21mm, Medela manufacturers the breast shields in five different sizes (21mm, 24mm, 27mm, 30mm, and 36mm). This particular breast shield is size small (21mm). Moms can choose the right size to fit their needs and experience ultimate comfort and pumping performance. Another great detail of the Medela PersonalFit Breast Shields, Small, 21mm, is the user can personalize their own pump to experience maximum milk removal. Professionals in the lactation industry all agree that in order to to be effective in milk expression, the right fit of the breast shield is important. For the user?s convenience, the Medela PersonalFit Breast Shields, Small, 21 mm, are compatible with all of the Medela breast pumps and come in a quantity of two to a package. Connectors for the breast shields are sold separately. ? Breast shield size is small (21mm) ? Made without BPA ? Available in 5 total sizes with two breast shields per package ? Compatible with a Medela breast pumps ? Breast shield connectors are sold separately ? Proper fit is recommended by professionals in the breastfeeding industry