If you look at the bottom of an iConnectivity interface you may notice there is a hole right in the middle. This hole is primarily used to screw your iConnectivity interface to a rackshelf. More specifically tailored for the iConnectivity rack shelf. If you have the rack shelf purchased directly from iConnectivity you will get the correct mounting screws with it. If you are using another brand and want to mount your iConnectivity interface you will want the correct size screw.
The screw size is 1/4-20. This is the same size as a camera tripod.