The bridge plug has a solid core that allows it to hold pressure from both directions. The frac plug features a oneway, internal check valve that is closed with a ball while the zone above the plug is fractured. The plug can be run with the ball in place, the ball can be dropped from surface when the plug is in position, or a caged-ball configuration can be used. The check valve allows free flow of fluids from below the plug after the stimulation operation is completed.