Aftermarket batteries for 1D mark III?

[Bass Sweden]

Hi guys
Just woundering if anyone has tried aftermarket batteries for the 1Dmk3?
Ive been using Sterlingtek batteries for my other cameras and those has acually been better than the orginal one.
But im having trouble finding backups for the mk3. I also saw warning on Canon site for aftermarket batteries for the 1D3, never seen that before.
Anyone tried any?

[Axel Hildebrandt]

I haven't seen any aftermarket batteries for the 1D3. I bought a second battery but haven't had to use it in the field since a charged battery lasts so long.

[Doug Brown]

I also own a Canon battery as a backup. They're such good batteries that IMO it's money well spent.