The Cisco Catalyst C2960X-FIBER-STK= Flexstack-Extended Network Stacking Module is designed for use with Cisco Catalyst 2960RX-24, 2960X-24, 2960X-48, 2960XR-24 and 2960XR-48 network switches. This network stacking module has two SFP+ ports that allow you to extend stacking over long distances.