7D Battery question

I saw some generic batteries on eBay for my 7D (they come with a grip), but I when I compare the numbers to my Canon battery they don't match.

Canon battery: 7.2V 1800mAh
Generic: 7.4V 2100mAh

I know NOTHING about voltage and amperage... is it OK to use these batteries?

I'm not entirely sure whether the voltage will matter, as I guess it should only be charged by the charger to the appropriate voltage.

The capacity (mAh) certainly doesn't cause a problem.

I'm stumped at what goes on with batteries and Canon, the generic batteries that were really cheap on ebay seem to last longer for both my 20D and 7D.

If you search the forum for 7d batteries there are some links about which ebay batteries to use. Only certain ones give the camera the data it needs to give an accurate reading of power left for the power meter. Other than that yeah the batteries will work but like phreeky said the charger may be discriminating and you may have to purchase a generic charger. AFAIK all the like batteries will work, but only some will charge with the Canon charger and even less will operate the battery meter on the camera.
-my .02

-Chris