Orthodontic silicone nipples for use with innovative EcoViking glass baby bottles. Nipples are vented to reduce air intake, spit ups, and colic. Made of medical grade silicone which is free from PVC, BPA, plastic and other toxins and chemicals. The nipples are compatible with EcoViking 120ml (4-ounce) and 240ml (8-ounce) standard neck baby bottles, which means they accommodate your growing little one.