The Vent-A-Matic is a durable and effective in-glass ventilator that can solve most ventilation requirements. The 101 Rotary Vent is equipped with a diffusing rotor which helps to prevent severe draughts and improve fresh air distribution within the room. The rotor also continues to operate whilst under its own inertia, even when air pressure on each side has been equalised. The 101 model is most commonly used in toilets, boats, caravans and sheds. Requires a 121mm diameter hole. It can be fitted to 4mm or 6mm single glazing, without the need to re-glaze. Useful when no opening is available or where leaving an open window has safety/security implications. Unlike the 102 version the 101 is not provided with radial shutter control. Designed for simple two part fitting into a glass aperture. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.