A roll cage is a specially constructed tubular frame built in or around the cab of a vehicle to protect its occupants from injury in the case of an accident or rollover.
Building a roll cage 101.
Adding diagonal main hoop support braces turns it into and 8 point roll bar.
The basic 4 point roll bar consists of a main hoop behind the driver two rear struts and an optional cross brace on the main hoop should you need it or the rules.
Shown here is a visual difference between your basic 4 point roll cage and an 8 point roll cage from the chris alston s chassisworks catalog.
The bars shown in blue are optional.
They are typically used to reinforce the vehicle and ensure that the passenger is protected in the event of an accident particularly if the car rolls.
A roll cage is a metal framework that can be built around the inside of a vehicle.