Difference between eGo, eGo Mega, and eGo-T?

[jagp06]

Does anyone here know if eGo and Go-Go batteries are interchangeable? I've used on eGo batts so far, but see some good prices on gogo versions!

 

[stevohump]

I understand that a ego mega battery is just like a ego battery but last longer cause its 1000mah. I want to know what the size difference is between the two. If any one knows could you please post the exact measurements. Thanks for the help