The front section of the cage can simply be bolted on as required.  The  advantage of this cage  is that the rear hoop is welded into position, meaning you can use weather gear and when you wish todo a trackday or motorsport event you simply bolt the front section on.  In some countries full rollcages are not compliant at the car inspection stage.  This setup gives you the 2 options.  
 
 
All roll cages are made from Certified roll cage tubing