Do any of you use wireless grips? I tether primarily using the common USB but am looking to go wireless, even if it takes a little longer to post in LR.

Not sure if this has been asked before but what is the primary difference between the two wireless grips?  Canon, even during the time of production, seemed scarce on the differences between the two and trying to find documents online about it is like trying to find a needle in a haystack.  Anyone have any info, besides one coming out earlier than the other?

Also, does anyone know why these grips are nearly nowhere to be found and have been discontinued when wireless grips for much older cameras are still being sold by Canon?

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Not sure why the manuals don't seem to be online. They probably are somewhere. The II model was little disappointing in that it still didn't offer 802.11n. There should be plenty of them second hand. I have the original one and it works fine but you need to shoot Raw + jpeg to get a reasonably fast response.