Your search for "SG300" revealed the following:
NEW NetworkTigers Rack Mount Brackets Kit for Cisco SF300 SG300 SG300X Switch
SKU: NSH-8992
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 12.99
• 15 in stock
Call if you need more
New For Cisco 1RU SG300 SG300X SG200 SG500 SG500X Rack Mount Brackets Kit
SKU: NSN-6195
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 12.99
• 27 in stock
Call if you need more