Abstract: An extension jamb for rapid attachment directly to a frame to form an extension on the frame, with the extension jamb having a top surface for engaging a frame, with the extension jamb characterized by having a transverse elongated recess therein and an opening in the extension jamb, with the opening temporarily holding a fastener in a ready-to-use condition, and the opening having a central axis substantially parallel to the top surface to enable one to drive a fastener through a portion of the extension jamb and into the frame to enable securing the extension jamb to the window frame.