Fuel Tank - What does "Safety Stopper mean?

Question: What does it mean in a VMAR model when I see the term "Safety Stopper"?

Answer: Beginning in mid 2004, the VMAR factory began a gradual change to a new 3 line tank with a metal overcap that aside from the convenience of a 3 line tank, helps prevent tank splitting due to overtightening of the stopper expansion bolt. The metal cap covers the end of the stopper like the older plastic disk units and also extends down and around the neck of the tank to prevent the stopper from being over compressed and splitting the tank. So, we call this new stopper and metal cap system "Safety Stopper" because it helps prevent the tank from splitting.