Hi, I just wanted to ask a quick question. I am a US citizen and my wife has applied I-751 in March 2012 for removing temporary condition. After the Biometrics, they sent us an extension of one year valid until June 2013. According to the details of the extension letter she can travel outside the country during its validity. My question is "Does she need to go to a local USCIS office to get some kind of stamp on her passport before traveling abroad for 5 months or the extension letter along with her old green card is adequate for her return to the US in December 2012.