An astragal for a wooden screen door is a piece of hardware that is attached to the edge of one of the doors in a pair of double doors. Its primary purpose is to cover the gap between the two doors when they are closed, providing a seal that helps prevent drafts, insects, or light from passing through the gap. It also helps to align the doors properly and provides a surface against which one of the doors can close. The astragal is to be installed on the inside of the inactive door so that the active door can open out.

Only one astragal is needed for double door setups.