receives top key 109 and bottom key 107 which are reciprocally shaped the generally all aluminum construction is painted white with paint that can be applied 2 3 thousandths of an inch thick and does not run so as to minimize unwanted paint bumps and the like however those skilled in the art will readily recognize that any smooth finish paint is satisfactory the curtain 102 of the invention is preferably a single ply polymeric curtain however the curtain may be a multi ply polymeric curtain or some other type of curtain which is impervious to the passage of water under high pressure the strips which are affixed to the edges of the curtain are preferably a polymeric material but those skilled in the art will recognize that they may be made from suitable non polymeric materials the strips may be affixed to the curtain in a multiplicity of ways such as those set forth in co pending application ser no 10 322 965 filed dec 18 2002 which is incorporated herein by reference the curtain may contain apertures in the edges which extend through the polymeric strips affixed to the edges alternatively the curtain 102 and strips 601 may include notches which do not extend through the curtain and.