Packing

An elongate strip packing member comprising:

• first and second lip sections adjoined to form a relatively broad planar head surface, each of said lip sections including a base having an outer lateral surface;
• said packing member having a groove between said bases extending the length of said packing member and opening downwardly away from said head surface;
• said first lip section further including a laterally outwardly depending sealing projection, said sealing projection having a generally laterally outwardly facing side surface and a lower surface, said lower surface being adjoined to the outer lateral surface of said base of said first lip section and, in a relaxed state, being generally inclined from its laterally inner to its laterally outer extremities at an angle so as to be non-downwardly inclined from the outer lateral surface greater than or equal to 90.degree. with respect to a line normal to said head surface, and said sealing projection being of such volume and transverse cross-section configuration that upon application of a generally laterally inward force to said side surface said sealing projection is deformed to form a cavity adjacent said lower surface, said cavity opening downwardly away from said head surface and forming a pressure trap.