Close coupled WC pan and 6/4 litres dual flush cistern with soft close seat and cover pack. Product Details Company Name Ideal Standard International NV Brand Name Della Model Number U3959 Maximum Flow Rate 4.5 litres Maximum Volume 6/4 litres Category WC Suites Available In United Kingdom Efficiency Rating Chart Company name:Ideal Standard International NV Model:U3959 4.5 litres 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.