Specifications  - Silicone - 9cm x 17cm x 4.5cm- Suitable for combined feeding - Natural shape modelled on a mothers nipple during breastfeeding - Improved NUK Anti-Colic Air System minimises proven to cause no colic* - Y-cut slit allows baby to control the flow of the feed         - BPA free Usage Clean and sterilize the teat thoroughly before first use and after each further use. Sterilize by using the NUK Steam Sterilizer to ensure the teat remains hygienic. Avoid damage to the teat by ensuring that sufficient water is used when sterilizing with boiling water (boiling for 5 minutes is sufficient). Do not clean teats and bottles in a dishwasher as detergents may damage them. Please softly squeeze vent before each use to ensure that it is open. Microwave sterilization may damage the material. In a microwave, filled or sealed bottles may become damaged or explode. Microwaves may heat a baby's feed inconsistently and can cause burns. Shelf Life: 4 years from production date - see stamp (applies when stored under dry storage conditions, at room temperature and shielded from direct sunlight). About The Brand  To make life easier, you have to understand it first. Since 1956 NUK has been listening to the trusted experts: midwives, doctors, nutritionists and especially mums and dads in order to learn about the needs of both parent and child in those precious early years. Anti-Colic wide neck silicone teats The First Choice+ Teats replicate a mother's nipple during breastfeeding. The extra soft tip easily takes on different shapes whilst also promoting the development of the mouth, lips and tongue. The orthodontic NUK shape, combined with the NUK First Choice extra wide lip support, makes it  easier to alternate between breast and bottle feeding. The improved Anti Colic Air System minimises infant colic caused by the harmful swallowing of air.