A hinged flexible strip closure having complementary fastener strips and wall webs connected thereto, with the strips and webs meeting along a common parting plane, and interlock hook structure extending across the plane from one of the strips into a complementary interlock recess in the other strip, a closing and separating slider being engageable with the strips and having retainer flanges engaging with shoulders adjacent to the webs, there being hinge grooves in said strips along juncture of the webs with the strips but avoiding thinning of the webs and the retainer flanges having inner edges which are so spaced from the web as to avoid interference with efficient hinging of the webs at the grooves.