mmWave 5G is a type of 5G that uses frequencies much higher than lowband and midband. It has very short range. With mmWave, you can't get service inside buildings. Most solid objects can block mmWave. mmWave is much faster than any other type of 5G and can reach speeds of up to 2 Gbit/s currently. mmWave is considered the least practical version of 5G since the range is so short and basically anything can block it.