Abstract: A weather strip for attachment to a jamb for engagement of a flexible portion of the weather strip against a closure member for example a door comprises an attachment portion of rectangular shape for attachment to the jamb and a flexible portion of blade-shape or cylindrical shape for flexible engagement with the door. The attachment portion is formed of an exterior thin wall surrounding a hollow interior with the wall being co-extruded with the flexible portion. The resultant body is thus relatively flimsy and is rendered rigid by the addition of a stiffener element inserted into the hollow interior defined by the walls.