The round white louvred ventilation grille from Zexum is designed to fit on the end of ventilation tubes measuring between 4 to 6 in diameter. Easily installed with the supplied reversible spring fixing legs, and the products tough durable plastic construction make for an easy to use model which requires little attention once installed. Featuring a detachable flyscreen behind the outer vents, this product is ideal for protecting your building against the unwanted ingress of small animals or objects, and is suitable for use both indoors and outdoors. Main Features: Fits tubes between 4 and 6 in diameter Easily installed with the provided self locking spring fixings and recess for mastic fitting Ideal for internal or external use Tough plastic design Flyscreen is removable for use with gas appliances Technical Specification: Size: 165mm dia (6-1/2) Free Area cm²: 115 cm² without flyscreen in 6 tube 4 (100mm) tube = 75cm² 5 (125mm) tube = 118cm² 6 (150