The McAlpine ARB-1 is a 4"/110mm Anti Back-Flow and Rodent Barrier Valve that is designed to prevent sewage or wastewater from flowing back into a building's plumbing system, which could lead to contamination and health hazards. This valve is particularly useful for properties that are located in areas with a high risk of flooding or where there is a risk of sewage or wastewater backing up into the plumbing system. The valve operates by allowing sewage or wastewater to flow out of the building's plumbing system, but preventing it from flowing back in. The ARB-1 valve also includes a rodent barrier, which helps to prevent rodents and other pests from entering the building through the plumbing system. This is particularly important in areas where rodents are a common problem, as they can carry diseases and cause damage to property. Overall, the McAlpine ARB-1 valve is an important component of any building's plumbing system, as it helps to ensure the health and safety of occupants and prevent damage to the property. ・ For use with any McAlpine rigid or flexible WC connector with 4"/110mm rubber outlet seal ・ For use where special measures are necessary for control of rodents as recommended in Approved Document H1 The Building Regulations 2000 (2002 Edition) ・ Prevents back flow when fitted to WC pans as long as they are connected to the correct configuration of drain and soil pipe on a system and comply with the current building regulations and BS EN 12056-2:2000. ・ Deters rodents from entering the building through WC ・ Can be installed horizontally or vertically