Catalyst 4500-X 32 Port 10G IP Base, Front-to-Back, No P/S C4KX-NM-8SFP+ Catalyst 4500X 8 Port 10G Network Module C4KX-FAN-R= Catalyst 4500X front to back cooling fan spare C4KX-NM-8SFP+= Catalyst 4500X 8 Port 10G Network Module C4KX-FAN-F= Catalyst 4500X back to front cooling fan spare C4KX-PWR-750AC-F/2 Catalyst 4500X 750W AC back to front cooling 2nd PWR supply C4KX-PWR-750AC-R/2 Catalyst 4500X 750W AC front to back cooling 2nd PWR supply C4KX-PWR-750DC-F= Catalyst 4500X 750W DC back to front cooling power supply C4KX-PWR-750DC-R= Catalyst 4500X 750W DC front to back cooling power supply C4KX-PWR-750AC-R= Catalyst 4500X 750W AC front to back cooling power supply C4KX-PWR-750AC-F= Catalyst 4500X 750W AC back to front cooling power supply C4KX-PWR-750DC-F/2 Catalyst 4500X 750W DC back to front cooling 2nd PWR supply C4KX-PWR-750DC-R/2 Catalyst 4500X 750W DC front to back cooling 2nd PWR supply