I'm off on a long haul flight on Saturday and wondered if an external battery pack can be used to recharge my iPad Pro. I've got a whole bunch of films that I want to get through and not sure if the plan will include a USB charger. Are there any particular features that I should look out for? I couldn't see any chargers that list the iPad pro in their list of compatible devices and not sure if it is because they haven't updated the literature yet or because it specifically won't work. Recommendations gratefully received and the "cooler" it looks the better as I'm pretty shallow.