Terry i wondered the same things. I thought regular pucks would be better. I only use the box when my wife rides and we never do more that decent dirt roads. Phil has probably put it through some rougher stuff and he seems content with its stability. The box comes with its own rack. Its stainless steel just like the side racks and it is sturdy.It replaces the stock rack. Here is a pic (red tape is holding hardware)
The bottom of the box has two c type clamps that look to me like they are made of the same stuff as the pucks. These are push onto the rack firmly. The lever in the bottom right hand corner on front of the box releases the lock (which is stainless) then the box snaps in place. The lever can then be locked.
Here is a pic of box on rack
If you like your Zega pros you will like the top box. Very nice quality. Touratech catches alot of grief over their prices but i like it and i know i've spent more money on worst things in my life.I hope the pics help
Almost forgot if you get the box when you order locks be sure to give them your key code so you will only need one key for all boxes.