USB-C to Dual DP Ports Adapter 2 in 1: For macOS: ONLY SUPPORTS MIRROR MODE cannot extend to two independent displays due to macOS system limitations. For Windows OS: Supports full dual-screen extension (SST/MST modes) when used with a compatible USB-C (Thunderbolt 3) port. Correct Setup: FIRST connect your monitors to the adapter, THEN connect the adapter to your laptop for reliable detection. 4K DisplayPort Output: Supports resolutions up to 4K@120Hz for a single monitor, or dual 4K monitors at 60Hz each (3840x2160) via DisplayPort MST technology. Also supports 1440p and 1080p@60Hz for smooth, high-performance visuals. (Note: 4K output requires your source device, monitor, AND cable to support 4K. Use a certified DisplayPort 1.4 or higher cable.)