These are sterilized, disposable baby bottles that are ready to use immediately after opening the capsule. They are delivered in a set of 4. ・No sterilization is required; ready to use immediately. ・Lightweight and compact, making them convenient to carry. ・The accordion-style bottle allows for free adjustment of the angle. ・The amount of milk is visible at a glance. ・The milk flow can be controlled in 3 stages. Materials: Cap & Bottle: Polypropylene Nipple: Synthetic rubber (silicone rubber) Capacity: 250ml (maximum scale capacity) Thank you for viewing.