Viega Filling Valve Set (Model 8310.74). It is a genuine replacement assembly specifically designed for Viega concealed cistern systems. 
Key Product Details
Application: Used for water intake regulation in Viega concealed cisterns, specifically variants 1H, 1L, 2L, and Standard 1S.
Inlet Type: Side entry.
Thread Size: 3/8" BSP plastic thread.
Included Components: The set is a complete model 8310.74 kit containing the filling valve, a flexible hose, and the filling valve holder.
Performance: Engineered for quiet refilling and consistent flush performance in both domestic and commercial installations.