The FlushDaddy Side Entry Anti-Syphon Adjustable Fill Valve with 1/2" Brass Tail is a component typically used in toilets cisterns.

Here's a breakdown of its features:

Side Entry: The valve is designed for side-entry installation into the cistern, meaning the water enters the cistern from the side rather than from the bottom.

Anti-Syphon: The anti-syphon feature prevents backflow of water into the supply line. This is important for maintaining hygiene and ensuring that the water in the cistern doesn't become contaminated with waste water. The anti-syphon design ensures that once the cistern fills, water does not flow back into the supply pipe.

Adjustable Fill: This means the float can be adjusted to control the level at which the cistern fills. You can change the water level to suit your needs, which can help with water conservation or efficiency.

1/2" Brass Tail: The tail is the part of the valve that connects to the water supply. The "1/2" refers to the size of the connection (1/2-inch) which is a standard size for many water supply lines. The "brass" indicates the material used for this part of the valve, which is durable and resistant to corrosion.

Overall, this product is designed to provide a reliable and efficient way to control the water fill in a cistern, with features to prevent contamination and adjust the fill level as needed.