The Ideal Standard SV81767 (also known as the Univalve Universal Bottom Entry Inlet Float Valve) is a genuine, popular replacement part used in many Ideal Standard, Armitage Shanks, and Sottini toilet cisterns. 
Key Features and Specifications
Type: Bottom-entry toilet fill valve (float valve).
Connection Size: Standard 1/2-inch BSP (British Standard Pipe) thread connection.
Operation: Features a quiet concentric ball valve mechanism designed to minimize noise during the filling process ("Hush Flow").
Maintenance: The valve body features a "twistlock" quarter-turn system, which makes servicing or replacing the internal diaphragm washer very quick and easy without needing to remove the entire valve from the cistern.
Compatibility: It is a universal replacement designed to fit a wide range of Ideal Standard cisterns, including models like the Alto, Concept 21, Sandringham, and Conceala 2 ranges.
Material: The main body and thread are made of durable plastic.
Status: This specific model number has been discontinued by the manufacturer and replaced with updated models (such as SV89567 or the delayed-fill version SR03167), but spare parts (like the diaphragm washer) are still widely available. 
The SV81767 is a reliable and straightforward replacement part known for its easy installation and effective, quiet performance in the compatible cisterns for which it was designed.