This review covers Carbon, which Bluetrek is calling the “world’s first carbon fiber Bluetooth headset,” and touting for its unusually light weight. The numbers don’t sound incredible on their own—0.29 ounces and 2.9” x 0.74” by 0.78” size—but they actually are: Carbon looks like a thin plastic tube with an oversized Home Button jutting out of one side, opposite from a silicone rubber-tipped earpiece.…