So you must get a laptop with at least HDMI 2.0 port to ensure 60Hz. Also, if you need to convert (e.g. from USB-c to HDMI) then you also need to make sure that your converter cable supports 60Hz@4k.

If you have no HDMI ports on your laptop but always wanted to hook up two 4K monitors, this is one way to do it. All in all, you’ll have all your needs covered with this simple $40 Baseus ...