Six millimetres of aluminium is for people who do not treat rocks as the exception. On a Hilux Vigo the transfer case hangs lowest in the middle of the chassis and, in rocky terrain, takes single hard hits rather than gentle scrapes.

6.0 mm aluminium. Rival specifies 6.0 mm aluminium in silver — half again as much material as the 4 mm plate in the same range. It deflects less on a point impact and keeps more material in reserve after a heavy strike. The trade-off is mass, added right in the middle of the wheelbase.

Installation. The fitting kit is included and the plate bolts to factory mounting points. At this thickness, a lift and a second pair of hands are worth having.

Fitment. Toyota Hilux 2005-2011 and 2011-2015. The catalogue name lists 2.5 l and 3.0 l diesel engines; the technical description refers to the Hilux Vigo 4WD 2.5.

Choosing between 4 and 6 mm comes down to how you drive: 4 mm covers gravel and forest tracks, 6 mm is what you buy when the underbody meets rock on a regular basis.