There’s pretty much zero options at the moment if you are looking for an extended battery for your T-Mobile Samsung Galaxy SII (SGS2 T989). You can of course grab a cheapie fake 3500mAh battery on ebay, but are you really getting 3500mAh? Is that battery safe to use? And of course, does it come with NFC within the battery?
The last question may be important to some since Google Wallet and other apps are bringing out NFC options. The stock SGS2 battery carries 1850mAh of power, which in most instances is a decent amount and should last you all day. Of course, usage patterns will affect the hours of battery time so if you see anyone mentioning they are getting days on on charge, take it with a grain of salt.