Available in 12 oz/350ml u0026 18.6 oz/550ml capacity, convenient for small puppies or longer walks, hikes and all outdoor activities. One-handed operation, unlock safety lock, press the water release button to fill the trough, turn on the water lock securely in position when you are done feeding. Sealing with silica gel gasket ensuring the bottle of ;water does not wet your bag. Made of high quality food grade materials, harmless and completely safe.