Standard Height, Rimless, Back to Wall, 6/4litres dual flush when used with the appropriate Conceala cistern Product Details Company Name Armitage Shanks Brand Name Contour 21 Model Number S3056 Maximum Flow Rate 4.5 l/min Maximum Volume 6/4 litres Category WC Suites Available In United Kingdom Efficiency Rating Chart Company name:Armitage Shanks Model:S3056 4.5 l/min The average flushing volume for dual flush WC Suites and Cisterns is calculated as (a + (3 × b)) ÷ 4, where a is the full flush value and b is the low flush value.