The Coxa Soft Flasks have many different sizes for many different uses! Whether you need small feeds, to large volumes for long days; there will be one for you! They are made from TPU (Thermoplastic Polyurethane) with a screw-top opening for fast refills and easy cleaning. It is BPA and PVC free. Coxa Soft Flasks are also dishwasher safe though we recommend hand cleaning for the longest lasting results.