An impact absorbing structure must be fitted behind the gearbox symmetrically about the car centre line with the centre of area of its rearmost face in between 250 and 300 mm above the reference plane and no less than 575 mm behind the rear wheel centre line.
It must be constructed from materials which will not be substantially affected by the temperatures it is likely to be subjected to during use.
The sole additional components allowed to be fitted on this structure are the rear wing pillars, the jacks, the towing eye, the engine cover and the floor and/or rear diffuser.
Source: 2014 Technical Regulations for LMP1 Prototype