a first end member including an outer surface and having a thin-walled cross section with an approximately planar central portion and an outer peripheral portion;

a second end member spaced from said first end member, said second end member including an outer surface and having a thin-walled cross section with an approximately planar central portion and an outer peripheral portion;

a flexible wall including opposing open ends, said flexible wall secured between said outer peripheral portions of said first and second end members and at least partially defining a spring chamber therebetween with a central axis that extends between said opposing open ends, said flexible wall including at least one convoluted wall portion disposed between said opposing open ends;

a first directional stabilizer ring supported circumferentially around at least a portion of said first end member for biasing at least a first portion said flexible wall in a predetermined direction approximately transverse to said central axis, said first ring including a first wall and a second wall, said first wall disposed axially outwardly from said flexible wall and in approximate alignment with said outer surface of said first end member, said second wall disposed toward said flexible wall and extending at an included angle of from about 5 degrees to about 85 degrees relative to said first wall, said second wall capable of biasing at least said first portion of said flexible wall in said predetermined direction approximately transverse to said central axis.