Abstract: Resealable zipper plastic bags have upwardly protruding support members on each side of the bag mouth which are engaged within downwardly opening channels of two opposed indexer assemblies. With the bag mouth under tension, a slider assembly engages the bag slider, moves it to a fully closed position, then advances the slider to a fully open position. The indexer assemblies are moved toward each other to relieve tension on the bag mouth and cause the mouth to splay open. An insert plate is inserted and rotated to spread the bag mouth for introduction of product through a product chute. Once full, the chute and spreader assembly are withdrawn, tension is applied to the bag mouth, and the slider assembly moves the zipper slider to a fully closed position. The bag support members are then released from the indexer assemblies and the product filled bag is discharged from the apparatus.