Use these wall mountable brackets to install a 19" wide device such as a patch panel, switch, shelf or other 19" rack mountable item on a wall instead of on a data rack. 

There are multiple heights depending on the quantity and height of the items you want to mount.  They are measured in U's (short for rack units, one rack unit is a hair less than 1.75 inches.) All rack mountable items are measure in rack units.  There are also different depths to accommodate equipment that may be deeper (front to back.)