a slider for actuating profiled closure tracks , especially for a bag , having a base and two flanks parallel to a median central longitudinal plane and configured for stressing the profiled closure tracks between a closed latch position and an open separated position . a longitudinal rib subdivides the internal space of the slider into two non parallel channels . a first axial end of the channels wherein the channels are convergent makes an input end of the channels , while a second axial end of the channels wherein the channels are divergent makes an output end of the channels .