If backup is second items in case the primary fails, then the only backup items I carry are related to fire starting. I use a lighter, and have carry several wind resistant matches and either firesteel or a sparky. That's pretty much my pure "backup gear".

I carry duct tape for blisters and repairs, and a first aid kits. I carry more Katadyn water tablets than I need, and I plan my clothing to keep me comfortable in expected conditions, and safe is reasonable worse case so some people might say I carry more clothing and absolutely necessary.


--Mark