These are part of the Lact-Aid nursing system and are meant to be used with the Lact-Aid Deluxe Kit. Package contains four (4) Nursing Training Units. Each 3-Piece Unit consists of: 1 Feeding-Tube Assembly 1 Bag-Clamping Ring 1 Bag Tube. You will need Lact-Aid bags and other accessories to use these items. The Lact-Aid Nursing Trainer is designed for intimate use by mother and baby. For health and hygiene reasons it is not returnable if the package is opened according to Amazon rules.