3/4" thick bracket deisgned to support a shelf with out any visible supports
 
12" projection, designed to support a 15" deep shelf
 
Leave a 3/4" void in a traditional box shelf or drill a 3/4" hole in a solid shelf to accept this bracket. 
 
Mounts to a standard 2x4 wood stud without any blocking
 
Mounts to s standard 3 5/8 steel stud with blocking in the stud void