Abstract: A slider for a slide fastener comprises a pair of wings defining a guide channel, one of the wings having a pair of lateral edge flanges. Each flange has a corner ridge extending along its inner base and engageable with upper leg portions of the respective row of fastener elements so as to restrain the latter from being tilted in the guide channel. Each corner ridge is chamfered at its front end, whereby a leading end of the opposed rows of fastener elements, when a pair of opposed fastener stringers is threaded through the slider, is smoothly introduced into the guide channel without having being obstructed by the front ends of the corner ridges.