When driving through deep ruts or over rocks you always have the risk of damaging the bottom of your vehicle. For older Land Rover models, there is a variety of protection available. For a relatively new model as the Discovery 3, this isn't the case.
Now, there starts to be some choice in what's available. Time for an overview of the underbody protection for a Land Rover Discovery 3.
ASFIR
ASFIR has fairly complete ground protection in 6mm aluminum. I've found some pictures of their stuff at TBR and also from a Discovery 3 owner. Some people think it's not strong enough.


Matzker
A very complete kit from Matzker in 5mm aluminum.
Bearmach
Although I couldn't find it on their website Bearmach also has underbody protection. I did see an advertisement of them on the backcover of the Land Rover Owner International magazine of February 2007.
Outback Import
Outback Import apparently also have complete underbody protection, from 8mm aluminum. The Land Magazine of January-February 2007 has an article on the Discovery 3 of Geoland, a Belgian Land Rover specialist that explains it has an Outback Import underbody protection. Actually, I'm not sure if this information is correct, because the pictures I found of the Geoland Disco3 show protection that is identical to the Maztker one. Unfortunately I couldn't find any pictures from Outback Import.

Mantec
Mantec only makes front protection (so it only protects the front side: the radiator and the engine, that's why it's also called a 'sump guard').

Land Rover
Land Rover sells the version (made by Mantec) that can be combined with a winch, Mantec themselves only sell the non-winch version.
Now, there starts to be some choice in what's available. Time for an overview of the underbody protection for a Land Rover Discovery 3.
ASFIR
ASFIR has fairly complete ground protection in 6mm aluminum. I've found some pictures of their stuff at TBR and also from a Discovery 3 owner. Some people think it's not strong enough.
Matzker
A very complete kit from Matzker in 5mm aluminum.


Bearmach
Although I couldn't find it on their website Bearmach also has underbody protection. I did see an advertisement of them on the backcover of the Land Rover Owner International magazine of February 2007.
Outback Import
Outback Import apparently also have complete underbody protection, from 8mm aluminum. The Land Magazine of January-February 2007 has an article on the Discovery 3 of Geoland, a Belgian Land Rover specialist that explains it has an Outback Import underbody protection. Actually, I'm not sure if this information is correct, because the pictures I found of the Geoland Disco3 show protection that is identical to the Maztker one. Unfortunately I couldn't find any pictures from Outback Import.

Mantec
Mantec only makes front protection (so it only protects the front side: the radiator and the engine, that's why it's also called a 'sump guard').

Land Rover
Land Rover sells the version (made by Mantec) that can be combined with a winch, Mantec themselves only sell the non-winch version.