The De Vielle Chimney Balloon Large is an inflatable balloon that fits snugly into your chimney, preventing warm air from escaping and cold drafts from entering your home. It's an eco-friendly way to improve insulation and reduce heating costs during colder months. The balloon stops down draughts and updraughts, and also prevents debris, soot, and bird mess from entering your home. It can be inflated with the pump provided to install, and deflated to remove. This allows for a little ventilation. The balloon is completely reusable. It measures 775x465mm.