Clothes dry as the moisture evaporates. The more air the flows past the clothes, the faster they will dry so it is very important that the air flows smoothly and easily into your dryer and back out again to the outside of the building. Air is lazy; it doesn't like moving around tight corners and through long duct runs or past crushed flexible ducting. Periscopes (not the ones in submarines) are hard, smooth, metal ducting that allows a dryer to be backed up against a wall without crushing the ducting and restricting the critical exhaust airflow. They are available in different lengths and configurations for almost any installation.
