A plastic bag having a zipper-type closure which includes opposing closure members which each has a plurality of projections. The projections of the closure members are configured for interlocking and sealing engagement when the zipper is closed. At least one of the projections on one of the closure members is in one embodiment made of a softer material than at least one of the other projections. In some embodiments, the soft projection(s) are not configured for close tolerance fit with complementary mating projections. In some embodiments, the closure is used in combination with a slider. The closure can include deformations for providing tactile or audible feedback against movement of the slider. The closure can include slider rails at a top edge margin to minimize the size of the slider.