EDIT: Ignore me. This is what the regulations say:
F1 2008 Technical Regulations wrote:3.13 Skid block :
3.13.1 Beneath the surface formed by all parts lying on the reference plane, a rectangular skid block, with a 50mm radius (+/-2mm) on each front corner, must be fitted. This skid block may comprise more than one piece but must:
3.13.2 Fasteners used to attach the skid block to the car must:
- extend longitudinally from a point lying 335mm behind the front wheel centre line to the centre line of the rear wheels.
- be made from an homogeneous material with a specific gravity between 1.3 and 1.45.
- have a width of 300mm with a tolerance of +/- 2mm.
- have a thickness of 10mm with a tolerance of +/- 1mm.
- have a uniform thickness when new.
- have no holes or cut outs other than those necessary to fit the fasteners permitted by 3.13.2 or those holes specifically mentioned in g) below.
- have seven precisely placed holes the positions of which are detailed in Drawing 1. In order to establish the conformity of the skid block after use, it's thickness will only be measured in the four 50mm diameter holes and the two forward 80mm diameter holes.
Four further 10mm diameter holes are permitted provided their sole purpose is to allow access to the bolts which secure the Accident Data Recorder to the survival cell.
- be fixed symmetrically about the centre line of the car in such a way that no air may pass between it and the surface formed by the parts lying on the reference plane.
When the skid block is new, ten of the fasteners may be flush with it’s lower surface but the remainder may be no more than 8mm below the reference plane.
- have a total area no greater than 40000mm² when viewed from directly beneath the car;
- be no greater than 2000mm² in area individually when viewed from directly beneath the car;
- be fitted in order that their entire lower surfaces are visible from directly beneath the car.
3.13.3 The lower edge of the periphery of the skid block may be chamfered at an angle of 30° to a depth of 8mm, the trailing edge however may be chamfered over a distance of 200mm to a depth of 8mm.
OT: I can't believe the technical regulations are actually written in word. OMG. LaTeX for the win.