C2960X-STACK

C2960X-STACK is a Cisco Catalyst 2960-X and 2960-XR Series Switches FlexStack Plus Stacking Module, which allows these switches stack with each other to offer flexible management.
FlexStack-Plus is the name of the stacking technology used by the Cisco Catalyst 2960-X and 2960-XR Series switches. FlexStack-Plus is specific to the 2960-X and 2960-XR Series of switches.