The POCO X7 supports Nano SIM + Nano SIM card slot, which is located in the bottom-left corner of the device.
A Nano SIM card is the smallest size of SIM card currently available. It is used in mobile devices like smartphones, tablets, and other mobile gadgets to connect to a cellular network. The size of the Nano SIM card is 12.3mm × 8.8mm, making it much smaller than the older Micro SIM and Standard SIM cards.
The Nano SIM card contains unique identification information that allows the device to connect to a mobile network for calls, messaging, and data.