auxillary heavy duty battery

[RapidRide2]

My vocab is weak what does gm mean by the term auxillary battery for an extra 125 dollars?  Is this an extra on board battery or just a heavier duty battery for a hefty extra $125???? this is for 2002's and 2003's by the way  thanks to all who help

[HillHound]

Auxilliary battery means an actual secondary battery.  Most people that get this option intend to use it as an extra electrical power for something like a slide-in bed camper or some mounted power tools such as a small air compressor or work lights.

[Stepside Z]

If you are ordering a truck or buying one off the lot this is a pretty good option to have. You never know when the extra power will be needed.