Tripp Lite by Eaton SmartRack SRRAILDPTH2U Mounting Rail Kit for Rack

Increase or Decrease the Depth of Your Server Rack by 4 in.
This SmartRack® rail-depth adapter kit lets you mount rack equipment so that it either extends four inches (10.2 centimeters) past the front vertical mounting rails or recesses four inches within the rails. This would benefit you, for instance, if you mounted extra-deep equipment that protruded out the front of the rack and prevented you from closing the door. Or it can allow you easier access to front cabling and help cut down on cable strain.

Easy Installation Using the Included Hardware
The SRRAILDPTH2U comes with two steel mounting brackets made from heavy-duty steel with a black powder-coated finish to mesh seamlessly with your rack. Connect the 2U extension brackets to the front rails using the included hardware. Position the brackets outside the rails to increase rack depth or inside the rails to decrease rack depth. Then mount the equipment to the brackets. The SRRAILDPTH2U is compatible with EIA-standard 19-inch open frame racks and enclosures.