ot that injury has been suffered by other, unidentified members of the class to which they belong and which they purport to represent." Montanez v. HSBC Mortgage Corp. (USA), 876 F. Supp. 2d 504, 512 (E.D. Pa. 2012) (citing Klein v. Gen. Nutrition Cos., 186 F.3d 338, 345 (3d Cir. 1999)) (finding a concrete and par