I've found a canon 40D which has BG-E2N battery grip as addition. However I don't have to buy it too. If I don't, I'll pay less.
At this point I've confused whether I gotta get it or not.
What positive sides does it has to be considered as an important accessary
Also I'm not sure about It's method of working. As far as I know to use it first we have to remove the original battery of the body and mount the battery grip but does it have its own battery or again we install the battery we removed from body to battery grip ?
As I said I'm not sophisticated about it, can you please clarify it

Just a tiny detail that goes a long way
