?Excellent after-sales service?It is our responsibility to ensure that every user has a great product experience and shopping experience. Therefore, if you encounter any problems during the use of this product, please do not hesitate to contact us , We will respond to your questions or problems as quickly as possible after receiving your email. ?Important notes?Only when your computer supports dual display or multi display, you can use this product to achieve 4 computers to share dual monitor. If your computer only supports single display, then this product cannot help you get dual display function. Our products include 8 HDMI cables, 4 USB-B cables, and 1 mini USB charging cable. When using the product, please make sure that all cables are connected tightly, and make sure that all cables are good. ?Support 2 Switching Modes ?1. Button switching: There are four switching buttons on the KVM panel. You can select the device you want to switch to. 2.Hotkey Switching:Hotkey command: Scroll Lock+Scroll Lock+1/2/3/4 or Ctrl+Ctrl+1/2/3/4. Tips: In the process of product switching, the signal source needs to re-identify the display information, re-output the image signal, and the window interface position will be restored to the default position. Please adjust the window manually. ?One Set Of Keyboard & Mouse Control 4 PCs Share Dual Monitor?This Dual Monitor HDMI KVM helps you control 4 PCs share 2 monitors (Extend display mode or copy display mode) by only one set of USB keyboard & mouse, under the condition of your computers or laptops support multi-display or dual display. If your computer has only one HDMI output, you can use a converter or conversion cable, such as VGA to HDMI converter or conversion cable, DVI to HDMI converter or conversion cable, etc. ?UHD 4K@60Hz Resolution?This small & exquisite kit supporting high resolution max up to 4Kx2K@60Hz, and also supports 3D and 1080P@60Hz or other lower resolution (Downward Compatible). Support most wireless keyboard and mouse (or mechanical keyboard) on market, plug and play, no extra power adapter required. Note: Only when both your source and monitor support 4K@60Hz then you can get 4K@60Hz effect, so if you want the max resolution you have to check your devices first.