[nosmohtac]

I'm not seidioseidio, but I can tell you it won't work with the mugen and their battery cover, unless it's made of some new morphing material.

Look at the pictures of the mugen and seidio extended battery covers. They aren't even close, and the mugen's battery cover goes much closer to the bottom of the phone making it unusuable with a seidio holster.

Where you might have some luck is if the Mugen battery is real close to the same thickness as the seidio 3200mah battery, you could get a sedio battery cover and then this case would work.