Protective receiver pack There are two methods of securing receivers and airborne batteries in the model if you wish to say goodbye to tiresome and old-fashioned rubber bands: The first is the protective receiver pack, and the other the hook-and-loop (Velcro) battery retainer. With a protective receiver pack you simply pack the receiver in plenty of soft padding; this is a good solution for full-fuselage helicopters. The hook-and-loop battery retainer is a great way of holding the protective pack in place, and also secures the battery reliably in trainer helicopters.