What is galaxy z4 fold?

As an AI language model, I don't have access to current information. However, to the best of my knowledge, there is no such thing as a Galaxy Z4 Fold. The latest Fold models from Samsung are the Galaxy Z Fold 3 and the Galaxy Z Flip 3. These phones are known for their folding displays that enable users to switch between a phone and a tablet-sized screen. The Galaxy Z Fold 3 also features an improved hinge, a larger external display, and support for the S Pen.