I played with car locks years ago. The norm uses brass tumblers. I will try and explain it to where it will make sense and hopefully you will realize it is no big trick.
Your key has 5 slots of different depths. I think there are also 5 different depths possible. There is a hole over each depth cut of the key. In each hole are two brass tumblers stacked one on top of the other. The combined height of each pair is the same. (meaning if it has a short lower tumbler, it has a tall upper tumbler) The bottom line is that when the key is inserted, all of the junction points between the pairs of tumblers line up and allow it to turn with a "stop plate" that will pass through the junctions.
Tough to explain but I hope this makes sense. The key code that comes with a new lock is in a code book that literally gives the depth combination in numerical line-up of the key depths.
