“SIM-free” means your iPhone doesn’t ship with a carrier SIM card. The SIM-free iPhone sold on apple.com and at the Apple Store is unlocked. That means you’re free to use a SIM card from any carrier that provides service for iPhone.
Apple has basically been offering this option as of late November when it started allowing customers to buy the iPhone X unlocked and unactivated. However, when you purchase the SIM-free model, you'll for sure be getting the iPhone X model with the Qualcomm modem, allowing you to connect to both GSM and CDMA networks.
You can purchase the iPhone X from the link below...