 Complete the following phrase:  Hell in a Cell is an annual gimmick pay-per-view PPV and WWE Network event produced by WWE since 2009, generally held in October. The concept of the show comes from WWEs established Hell in a Cell match, in which competitors fight inside a 20-foot-high roofed cell structure surrounding the ring and ringside area. The main event match of the card is contested under the Hell in a Cell stipulation. The 2021 event was moved from the October slot to June, which was only the second time for the event to not be held in October; the first time was the 