The Baxi connection tail is designed for use in the isolation valves of Combi, Duo-tec, Duo-tec ErP, Megaflo, Megaflo ErP, Platinum, Platinum +, Platinum ErP, System, System IE, Main Combi or Combi HE, Main Eco, Main Eco Elite, Main Eco Elite ErP, Main HE, Gold, Gold ErP, Heatmax, Performa, Promax, Promax ErP, Titanium and Titanium ErP boilers. The isolation valve, which is typically located beneath heating appliances, allows the user to control the flow of gas and water into a central heating system. It also enables the user to halt the flow in the event of a leak or an emergency.