100mm / 4 inch round rear spigot. Stainless steel exhaust outlets with gravity flaps. Easily connects to either flexible hose or rigid ducting. Weather seal to prevent unwanted leaks and drafts with 4 gravity flaps. Stylish and durable with an unobtrusive profile. Its stainless-steel construction protects against weathering such as; corrosion and rusting, prolonging the lifetime of the grille., Manufacturer: Kair