How to Get security Code for XTOOL X100 PAD ?

When i change the mileage for my car 2008 Chevy Express Cargo Van, X100 PAD ask for security code, where can i get it?

Enter into this page, and you will read the code. Send this code with your car exactly year and model to sales@obdii.shop . We will send these information to XTOOL company to calculate the code and resend it to you. Only GM series vehicles need this.