Features: -Neat treated seams and maximum tightness, no air leakage, optimal energy efficiency. -Easy to install, without glue, thermal bonding. -Premium protection, filter class G4, 8 mm thick, optimal filtering of the air. -For exhaust valve or butterfly valve ventilation units, for bathroom, guest toilet ventilation, air conditioner, automobile engine system. -Compatible with Maico, Pluggit, Zehnder, Helios, Wolf, Stiebel, CleanAir M4-1085 and much more. Specification: Length: 180 mm Thickness: 4 mm Diameter: 125 mm Filter class: G4 Colour: white Package Included: 20x Conical filters .