Clever, Dual Flush Cisterns Affordable can still be clever, especially when it comes to the Essentials cistern. It contains an internal overflow meaning that should water overflow then it ll simply run back down into the pan saving the need for an external overflow too. It also has an inlet positioned on both the left and right hand side for convenience during installation and a fantastic dual flush mechanism. The dual flush will allow you to save water by choosing to use either a 3 litre eco flush or a larger 6 litre flush. Vitreous China Manufacturing The secret to the finish and durability of these products is the manufacturing process of the vitreous china and then their gorgeous gloss finish. It provides you with a stain and scratch resistant surface that's easy to clean and.