With the 3390's interchangeable covers, bargain pricing, and features such as mobile messaging, it's not hard to figure out that Nokia is targeting teens and other youthful folk with this model. Even so, this model has enough high-end features--including voice dialing and a vibrating ringer--that it will also appeal to a more mature audience.The 3390 looks similar to Nokia's 8260 and 8290 handsets, but it's slightly bigger, weighing 4.2 ounces and measuring 4.3 by 1.9 by 0.8 inches. Apart from size, the main differences between the 3390 and those two models are the 3390's function keys (it has three instead of six) and its interchangeable Xpress-on covers. The 3390's three keys allow you to maneuver through the phone's menu and make calls. Like the 8290, the 3390 also has a backlit keypad, and although the keys are small, they're spaced far enough apart to prevent misdials.