Your search for "QDD-400G-FR4" revealed the following:
Cisco QDD-400G-FR4-S 400GB BASE-FR4 Duplex LC 2km Duplex SMF QSFP-DD Transceiver
SKU: NSB-2430
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 367.99
• Only 2 remaining
Call if you need more
NEW Arista QDD-400G-FR4 400GB BASE-FR4 1310nm SMF 2km QSFP-DD Transceiver
SKU: NSN-6734
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 437.99
• Only 2 remaining
Call if you need more
Arista QDD-400G-FR4 400GB BASE-FR4 1310nm SMF 2km QSFP-DD Transceiver
SKU: NSB-5245
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 429.99
• Only 2 remaining
Call if you need more