Kair Louvred Grille 100mm / 4 inch with Flyscreen Plastic 100mm / 4 inch air exhaust outlet round vent with fixed louvres and insect screen. 4 inch / 100mm round male spigot on the back of the grille fits inside most comparable size pipes/hoses such as Kair 100mm Round Female Duct Pipe Part: DUCVKC250 or 102mm flexible hose Part: DUCP002/102/35. Easy to install just push-fit together & seal if required using a method of your choice (Popular options include Mastic Sealant Poly Cement or Tape).