The Viva Skylo 4-in-1 Filling Valve is a highly versatile and universal toilet cistern fill valve designed to be a single solution for nearly any installation requirement. It integrates four key functions into one unit, making it a favorite among trade professionals for repairs and new builds. 
The Four Functions Explained
The "4-in-1" refers to the valve's ability to adapt to different plumbing configurations using the components included in the box: 
Bottom Entry Installation: It can be configured for a water supply coming up through the base of the cistern.
Side Entry Installation: It can be easily switched to accommodate a water supply entering from the side of the cistern.
1/2" UK Thread Size: It comes with the standard 1/2-inch BSP thread size used widely across the UK and Ireland.
3/8" European Thread Size: It includes an adapter to convert the connection to the smaller 3/8-inch BSP thread, common in European plumbing systems. 
Key Features and Benefits
Universal Compatibility: With both entry options and thread sizes covered, this single product can replace almost any existing fill valve, reducing the need for plumbers to carry multiple variations.
Water Saving (Delayed Fill): The mechanism delays the main cistern filling process until after the flush cycle is complete, helping to save water and reduce water bills.
Compact & Adjustable:
It is height-adjustable (telescopic) to fit various cistern heights, usually between 9 and 14 inches.
The float can rotate 180 degrees, allowing it to fit into extremely tight or unusually shaped cisterns without snagging.
Quiet Operation: It is designed for quiet refilling, operating efficiently across a wide pressure range (0.25 to 16 bar).
Durable Build: It is available in models with either a plastic or a heavy-duty brass shank to prevent cross-threading and ensure longevity.