A one-piece, sloped baffle includes a generally cylindrical central opening having a central axis extending between an open circular end and an open elliptical end. A plane defining the open circular end is perpendicular to the central axis. A plane defining the open elliptical end is at an oblique angle relative to the central axis. The baffle further includes an opening extending between the ends and a pair of opposing edges substantially parallel with the central axis and on opposite sides of the opening. First projections are positioned on opposite sides of the opening and aligned with the opposing edges. Second projections are positioned on opposite sides of the opening at a radial distance from the first projections. The baffle further includes a plurality of grooves that extend circumferentially around an inner surface of the baffle.