below the plateaus opposing grooves define a lower chamber 54 having a generally rectangular profile during slider insertion the zipper and upper marginal portions of the bag panels 4 a and 4 b enter the gap g with the zipper closure profiles 28 and 34 residing in the lower chamber 54 of that gap the lower flange 26 of zipper strip 8 a extend below the bottom of the slider while the upper flanges 24 and 30 of zipper strips 8 a and 8 b respectively extend through the narrow section of the gap between the opposing plateaus and into the upper chamber 56 of gap g the slider shown in fig4 and 5 has a finger 50 for stopping the slider from sliding off the ends of the zipper the finger 50 projects vertically downward from the underside of the slider bridge 46 into the upper chamber 56 of the gap g as shown in fig5 the finger 50 extends between the upper flanges 24 and 30 and between the uppermost portions of panels 4 a and 4 b joined thereto that form the mouth of the bag i e the finger 50 extends into the bag mouth see also fig6 but not between the closure profiles 28 and 34 the finger 50 may have the shape of a plate one end of the plate shaped finger coming into contact with a side seal 60 see fig6 at one end of the mouth when the slider is moved continuously in one direction and the other end of the plate shaped finger coming into.