We recommend you use this Ardex Adhesive X7G Plus with all the Light Weight Building Stone. It is grey in colour. The Ardex Adhesive X7G Plus is specifically formulated to have a very high yield per bag (Ceram Research has confirmed approximately 20% more coverage per kg compared to traditional tile adhesives) along with enhanced properties of adhesion and flexibility. The Ardex Adhesive X7G Plus is sold per bag (18kg) at just €25 plus vat (excluding delivery). Each bag covers approximately 5m².