judging by it looks... its sumthin like the G1 seido batt.... one thing u should pay attention is that after the huge back cover in place, will it affect the volume of the phone?? mine G1 is...by 40% other than that, the cover actually quite fragile if you always place ur phone in ur pocket...as it quite hollow between the extnd batt... apart from that, very happy with my batt performance... this is a t-mobile G1 experience for ur reference...

there is some info i heard that the extnd batt which not the bulky type was not so good....thats why go for the bulky ones...

i think the highest capacity for non bulky one is 1600mah gua...