This is a set of 4 bottles. All items are unused. The slim design is optimized to reduce air resistance, making it ideal for TT bikes and aero road bikes. Simply attaching them to the down tube will streamline the airflow around the frame, reducing air resistance. These are not in stock at every shop, so I'm including two extra bottles. This provides peace of mind in case one breaks if dropped. These are being sold at a special price due to being an older model. The items in the images are everything included. Please note that there may be some scratches from storage as these are imported goods.