Advanced models may support multiple active standby connections, meaning all six numbers can receive incoming communications at once.
If you absolutely need six physical slots for a specific industrial use case (e.g., a mobile test lab), you will need to purchase a or a SIM bank router —a device that looks like a modem, not a phone. a mobile test lab)
The "proper piece" for a device typically refers to the SIM card tray or SIM reader specific to that model. Depending on your device, here are the exact parts and support resources you might need: Replacement SIM Card Trays a mobile test lab)