This is a EMT pipe holder to hang Christmas Lights on. This was designed for 3/4" EMT pipe. The mounting holes are angled slightly towards the center to ensure you can get your drill in there. These are available in lengths of 2", 3", 4", 5" & 6". The length is from the mounting base to the center of the pipe.
Two designs for 3/4" EMT pipe are now available. Links to the designs are included below: