Your search for "540-020908" revealed the following:
For Juniper EX-RMK 540-020908 EX Series Switch Rack Mounting Kit
SKU: NSB-8442
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 39.95
• 89 in stock
Call if you need more
Juniper EX-RMK 540-020908 EX Series Switches Rack Mounting Kit
SKU: NSH-4938
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 105.99
• 6 in stock
Call if you need more