Which models of extended SRAM cassettes can I use with MELSEC iQ-R series CPU modules?

You can use “NZ2MC-1MBS”, “NZ2MC-2MBS”, “NZ2MC-4MBS”, “NZ2MC-8MBS”, “NZ2MC-16MBS”,and “NZ2MC-8MBSE”.
You cannot use extended SRAM cassettes for the high-speed universal model QCPU.