-1 gram ([mass: [real number: ["0.-2147483648"]]; [ounce]])
basically bandwidth, its quicker than most BroadBand or cable connections.
3G means the download speeds can reach up to 3mb per second. 4G means the speeds can be 100 times faster than 3G. 4g speeds are targeted to be in the 100Mb per second to 1 Gb per second range.
4G can get Internet underground much faster than 3G can, and you can e-mail on an underground train.
4G is much faster.