This article explains the concept of the wall or arrowhead defense in ultimate frisbee. It is a form of zone defense that forces the offense to throw over the defense and limits the chance of a huck. The offense will generally have to take shorter throws and gain yards by moving the disc around the field. The wall or arrowhead defense uses a series of defenders in a line to block the throwing lane and prevent deep throws. Defenders in an arrowhead formation can also form a triangle to prevent short throws. The article provides detailed instructions for setting up a wall or arrowhead defense, discussing the positioning of each defender and offering advice on how to adjust the defense when the offense changes their strategy.