arrow s in the operation of the locking closure l2 the zipper slider 18 is moved in the direction of the arrow r to the right as viewed in fig8 using the pull tab 21 into the closed position of fig8 to close the bag opening 13 after packaging or after partial use of the materials within the bag b the pull tab 21 is then pivoted downwardly in the direction of the arrow a in fig9 over the camming surfaces 61b 62b permitting the fingers 61 62 to flex and yieldingly enter the pull tab opening 22 as the pull tab is moved further downwardly the spring fingers yieldingly flex inwardly and the edges of the pull tab opening 22 slide over the camming surfaces 61b 62b when the pull tab 21 is moved past the camming surfaces 61b 62b the fingers 61 62 are released to move laterally outward for locking engagement of the pull tab with the notches 61a 62a as shown in fig1 thus the zipper z is releasably locked in the closed position of fig8 presenting a serious obstacle to any efforts by a child attempting to open the bag as in the previous embodiment the child resistant feature of the invention is readily apparent in the embodiment of fig8 10 to release the zipper z from the locked position.