The nipple is produced from soft natural rubber latex and designed with an anti-colic valve, to ensure the best milk flow for your baby.BIBS Bottle Nipple is designed with a heart-shaped anti-colic valve, to ensure the best milk flow for your baby combining both function and aesthetics. BIBs Bottle Nipple Latex 2 Pack Slow Flow.Features:The nipple has been specially developed to match the nipple from our popular BIBS Colour pacifier which promotes the right sucking technique for successful breastfeeding, to avoid confusion if you are both breastfeeding and supplementing with a bottle.