The Fluidmaster 400EL 3/8" B/E Brass is a professional-grade, bottom-entry toilet cistern fill valve, specifically designed for the European market with a smaller connection size than the common UK standard. It is highly regarded by plumbers for its durability and quiet operation. 
Key Features
3/8" BSP Brass Shank: The primary feature is the heavy-duty, 3/8-inch British Standard Pipe (BSP) brass threaded shank. This material prevents the common problem of cross-threading often encountered with plastic shanks and ensures a secure, long-lasting connection.
Universal and Adjustable: The valve is height-adjustable from approximately 230mm to 355mm (9 to 14 inches), allowing it to fit seamlessly into most bottom-entry cistern configurations, including compact and modern 6-litre designs.
Ultra-Quiet Operation: Engineered with noise-reduction technology, it is one of the quietest fill valves available, minimizing refill noise and water hammer (banging pipes).
Anti-Siphon Design: It incorporates an anti-siphon feature to prevent the contamination of the fresh water supply, ensuring compliance with water regulations.
High and Low Pressure Compatibility: The valve operates effectively across a wide range of water pressures, making it versatile for various plumbing systems without needing seal changes.
Fast Refill with Absolute Shut-Off: It provides a quick and efficient refill cycle and achieves a reliable, absolute shut-off after every flush, preventing water waste.