Features: It'S A Whole New Pumping Experience, Personalised For Mum. Its Available In 4 Different Sizes For Maximum Comfort And Pumping Efficiency - 21Mm, 24Mm, 27Mm And 30Mm. The Rim Of The Breast Shield Is Made With A Soft, Natural-Feeling Material That Lays Smoothly On The Breast For Comfort. Battery Required: No Description: With The Personalfit Flex Breast Shield You Can Easily Adapt The Way Your Breast Shield Fits To Help You Find The Most Comfortable, Most Efficient Position To Pump, Even As Your Breast Shape Changes.