Window sock

A window sock is a fitted mesh cover that slides or clips over a car's door frame where the window would normally close, letting you crack or fully lower the window for airflow while keeping mosquitoes and other insects out. It typically zips or has an opening for the door handle so the door can still be used normally.

It solves a specific car camping problem: rolling a window down for ventilation on a warm or humid night usually means choosing between fresh air and bug-free sleep, and a window sock removes that trade-off. Most are made for one specific door shape or a small range of vehicles, since fit against the frame is what keeps insects out.

When buying, check the fit against your specific vehicle model rather than assuming a universal size will seal properly, since gaps at the corners let bugs in regardless of mesh quality. A common mistake is treating window socks as a substitute for a full tailgate tent's mosquito netting, when they only cover the window opening rather than the whole sleeping area.