Your search for "A900-IMA4OS" revealed the following:
Cisco A900-IMA4OS ASR 900 Series 4x OC3/STM1 or 1x OC12/STM4 Router Module
SKU: NSH-6116
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 758.99
• Only 2 remaining
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NEW Cisco A900-IMA4OS ASR 900 Series 4x OC3/STM1 or 1x OC12/STM4 Router Module
SKU: NSN-5573
Condition: New
Shipping: Overnight Options
Warranty: 365 days