Your search for "EX4500-PWR1" revealed the following:
Juniper EX4500-PWR1-AC-BF EX4500 Series 1200W AC B-F Airflow Power Supply
SKU: NSH-7157
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Juniper EX4500-PWR1-AC-FB EX4500 Series 1200W AC F-B Air Switch Power Supply
SKU: NSH-5385
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days