Neck Adaptor (Square to Round) ModelNeck Size (mm)Spigot Size (mm) QSM-NASR-45150450x450Ø 150 QSM-NASR-45200450x450Ø 200 QSM-NASR-45250450x450Ø 250 QSM-NASR-45300450x450Ø 300 QSM-NASR-45350450x450Ø 350 QSM-NASR-45400450x450Ø 400 QSM-NASR-45450450x450Ø 450 Description The LinkedAir neck adaptor (Square to Round) is made out of galvanised steel and used for the connection of round duct. Black paint internally. These are commonly used with our QVE Ceiling Diffusers range. Custom sizes are available upon request. Product Code QSM-NASR