These Vaillant white 45 degree plume elbows are for use with a plume management kit if more bends are required. They help direct he exhaust gases emitted from the boiler away from windows, doors, or other areas where it could be a nuisance or cause damage. By using these elbows, the installer can reroute the flue gases to a more suitable location. This helps in managing the plume and ensuring that the boiler operates efficiently and safely while complying with local regulations regarding flue gas emissions. NEW Vaillant White 45 Degree Plume Elbows (Pair)