55mm threaded hole, 55mm unthreaded hole, 55mm slotted hole, 110mm threaded hole, 110mm unthreaded hole and 110mm slotted hole. All brackets stated are suitable for each type of ceiling track referred in this  manual. 

For ceiling track installation, the threaded track bracket is the first choice to use, with the unthreaded bracket  an option used with turntable fixings. (depending on the turntable mounting hole state) the 55mm is the  standard bracket to use to suspend a track, and the 110mm being used to link two tracks together. The track  brackets will be supplied with wedges which are fitted to secure the ceiling track to the bracket.