The PERIBOARD-409 U is a USB keyboard which offers a 5.9 ft long cable. It has compatible with Windows 7, 8, and 10. If you are facing any issues with double lettering please adjust your computers settings as described below: 1. Open the "Control Panel" and click Ease of access Center, Click Make Keyboard Easier to Use, Check Turn on Filter Keys under Make it easier to type, Apply these setting. 2. Go to Keyboard Properties in Control Panel. Adjust Repeat rate faster, click Apply and Ok. Then, test if the issue is resolved. If you are still facing these issues please contact us directly so we can assist you further.