How do the extended batteries compare in physical size?

[dlswaim]

I have read the forums on extended batteries for my Droid Bionic, which cover capacities, dependability, and other issues. I am trying to find out how they compare in actual size. The back covers from the various manufacturers vary greatly in design, but could an OEM back cover for the OEM extended battery also fit with, say, the Seidio extended battery?

 

[alnaintl]

External batteries can vary in sizes... The ones they sell at this site are about 4 inches. So that is just a bit smaller than an iPhone. Extended Battery and Portable Battery Solutions