To get 4K at 60Hz with the Aluminum Type-C to HDMI Adapter, use a display that supports 4K 60Hz and connect it with an HDMI 2.0 cable. If 60Hz does not appear in your display settings on a Mac, set it manually:

1. Open System Settings.
2. Select Displays.
3. Hold the Option (Alt) key and click Scaled.
4. Choose your desired resolution.
5. Check Show low resolution modes if needed.
6. Select the 60Hz refresh rate.

Your Mac should then output a crisp 4K picture at 60Hz.