Your search for "845398-b21" revealed the following:
HPE 845398-B21 25 Gigabit BASE-SR 100m SFP28 Transceiver
SKU: NSB-1550
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 125.99
• Only 2 remaining
Call if you need more
NEW HPE 845398-B21 25 Gigabit BASE-SR 100m SFP28 Transceiver
SKU: NSN-2434
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 199.99
• 65 in stock
Call if you need more