One important thing to note is that it doesn't have a 'ball' on the valve like most water systems - these 'ball' systems can harbour bacteria which is not sanitary for your birds.
The variable valve is for use by the smallest of birds. It is recommended for finches, canaries, lovebirds, doves, and other birds up to cockatiel size. This valve is designed with the ability to adjust its sensitivity, allowing the water to flow more easily for the very small birds or less easily for the cockatiel-sized birds.
Size: 7oz water system
**Please ensure that your bird is drinking from the bird butler before removing the water bowls. Check Bird Butler regularly to make sure that water is flowing properly**