First you need to find out what phone you have. If you have an iPhone 6 or below or an Android, you need to buy ones with a 3.5mm round headphone jack. This is the type you still use on planes. For 7s, 8s, Xs and all the other recent variations, Apple ditched the round jack and replaced it with a USB lightning port. In truth, both are heading for extinction - the future is bluetooth wireless earbuds.