If you know the Nokia 8110 4G, you already know what a 4G feature phone is like. Think of your regular basic phone with an alphanumeric keypad, and add a 4G modem inside: you have a 4G feature phone.
It can make calls and manage SMS, has a few tools, play a few basic games, and can also connect to fast 4G wireless networks for web browsing, downloads and HD voice calls.
The Nokia 220 4G does not run KaiOS though. It runs something that Nokia calls Feature OS. The display is a 2.4-inch TFT screen. On the specs list is a VGA rear camera, 24MB internal storage, 16MB RAM, a dual-SIM slot, Bluetooth 4.2, and a 1200 mAh removable battery.
For network connectivity, there is no 3G, so when out of 4G coverage area, it falls back to good old 2G. Only GSM 900/1800 and European 4G bands are supported though. The Nokia 220 4G is in Mint Blue or Black and costs a mere €39 (about $45 USD).