It is a promo code from Gigabyte.

To redeem your promotional code for Gears of War 4 please follow the steps below:
Enter your coupon code and date of birth on https://redeem.geforce.com/
Agree to the terms and conditions.
Click 'Sign In'.
You will be taken to the Microsoft account portal. Sign in or create a Microsoft account, and agree to allow NVIDIA access to your profile and to perform product key redemption.
NVIDIA will begin to 'link' your account. This can take up to 30 seconds.
When complete, you will be taken back to the redemption portal and your Microsoft account username should now be visible. Please verify that it is the account you wish to redeem to.
Continue with the redemption until complete.
After redemption, your game will be visible inside the Windows Store app.
To view this, click on your user picture and select "My Library". Gears of War 4 will be listed under the "Games" category.

You will need to go first. Add me if you have any questions.
Feel free to add for quick trade.

Please leave a comment on my thread before adding me.