Your search for "ws-f6k-dfc4" revealed the following:
Cisco WS-F6K-DFC4-EXL Catalyst 6500-E DFC4XL Distributed Forwarding Card
SKU: NSH-5362
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 817.99
• Only 2 remaining
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NEW Cisco WS-F6K-DFC4-EXL Catalyst 6500-E DFC4XL Distributed Forwarding Card
SKU: NSN-0550
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 7,187.99
• Only 1 remaining
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Cisco WS-F6K-DFC4-E Catalyst 6500 Distributed Forwarding Card
SKU: NSH-2559
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 95.99
• Only 2 remaining
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Cisco WS-X6848-SFP-2T Catalyst 6800 48x 1GB FC SFP Switch Module w/ DFC4
SKU: NSH-2176
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 551.99
• Only 2 remaining
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NEW Cisco WS-X6848-TX-2T Catalyst 6800 Series 48x 1GB RJ45 Switch Module
SKU: NSN-1458
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 437.99
• Only 2 remaining
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Cisco WS-F6K-DFC4-AXL Catalyst 6500 Series DFC4XL Distributed Forwarding Card
SKU: NSH-6092
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days