A frac plug has a bottom shoe, a single slip ring supported by the bottom shoe, a slip wedge positioned above the slip ring and axially movable relative to the slip wedge, a radially outwardly expandable sealing element supported by the slip wedge and a deformable backup shoe fixed to the sealing element. The deformable backup shoe has a cap covering at least a portion of a top surface of the sealing element and an outer leg extending along at least a portion of an outer surface of the sealing element. A ball seat is insertable into the radially outwardly expandable sealing element.