Use the TeraFlex JL 4xe: Alpha Speaker Bracket Kit to retain the rear speaker in the factory Pedestrian Warning System of your JL Wrangler Unlimited 4xe (4-door plug-in hybrid) with Alpha HD Spare Tire Carrier Mount Kit. The Pedestrian Warning System features an exterior speaker at each end of the JL Wrangler Unlimited 4xe (one in the right front wheel well and one behind the factory spare tire carrier) to warn pedestrians that the plug-in hybrid vehicle is running.