The Simon Vent-A-Matic model C102S is a pull-cord operated non-electrical fan, shuttered for toilets, boats, caravans and sheds etc with stormguard included for enhanced weather protection.All Vent-A-Matic models are designed for simple two part fitting into the glass aperture. For additional security and weather tightness, a little silicone glazing sealant can be applied to the external retaining ring. Equipped with a diffusing rotor which operates with the slightest differential in air pressure. For use with single pane glass. Aperture 121mm. Stormguard for weather protection Vent-A-Matic ventilators can be cleaned with normal window cleaning materials.