Transom is the result of a complete re-imagining of what a window fan should be. The air chamber abundantly draws fresh air from the outside in - or reverses electronically to exhaust stale air out. Powerful airflow circulation and comfort at half the height of conventional window fans, Transom is easy to install, blends elegantly into the space and preserves your view. Transom seals off windows 26" to 40" wide with the patented Soft-fit System that provides a sleek, satisfying and snug fit from end to end, without having to remove your screen. Transom â a new kind of window fan.