https://wccftech.com/great-news-apple-watch-series-4-is-compatible-with-series-1-2-3-bands/

In case you were wondering: yes, your current Apple Watch band will be compatible just fine with he Series 4 model.

On a very serious note, the Apple Watch Series 4 is a huge upgrade thanks to the inclusion of several new features such as the larger Retina display as well as an ECG sensor. But the story doesn’t end there – Apple went right ahead to tweak the design slightly that leaves the end user with a marvelous looking wearable that is sure to make a statement.