Extended battery size difference?

[Ruggybear]

Just got an Evo 4G and bought the 2600ma Sprint extended battery to go with it. Now the problem is finding a case/belt holster. I found one that seems pretty good from Seido but it says that it is specifically made for their 3500ma extended battery. Does anybody know if there is a thickness difference between the 2600ma Sprint battery and the Seido 3500ma battery?