COMPATIBILITY WITH DEVICES THAT USE THE ROUND 3.5MM JACK - not the flat lightning jack - But there are adapter options
If you have an iPhone 8 or high, ipad, or many of the other newer phones that have changed from the round plug in to the flat lightening jack, you will need to order a Lightning to 3.5 mm Headphone Jack Adapter (generically called a dongle) directly from Apple. (This link will open in a new window.) It's quite inexpensive and works far better than anything we found on Amazon. We know from personal experience.
If you want to purchase elsewhere just search for Lighting to 3.5mm Headphone jack (Note, you don't have to have an Apple product to use the Apple Adapter, we're just listing it because out of 3 we ordered, this is the one that proved to work)
The standard 3.5mm jack can be used with most smartphones, laptops, tablets and other electronic devices, including most cell phones (Exception iPhone 8 and above, iPod, MP3/MP4 players, desktop computers, notebooks and laptops, and tablets and other newer phones.