3" ID Wall Eye - Fits Barrier Thickness Ranging from 1" - 1 1/2" in Thickness. This unit will create a dressed, aesthetically pleasing hole through a wall, ceiling, floor etc., allowing the running of cables, cords, wires from one side of a barrier to the other with ease. This 3" ID unit fits into a pre-drilled hole 3 7/8" in diameter. This hole size will allow 1/8" of clearance to aid with alignment when installing the units.