There are five HDBaseT classes. Classes differ based on the maximum supported distance per resolution and cable type.

Class A supports:
4K, upto 70 meters over Cat5e cable
1080p, upto 100 meters over Cat5e cable

Class B supports:
4K, upto 35 meters over Cat5e cable
1080p, upto 70 meters over Cat6a cable

Class C supports:
4K, upto 100 meters over Cat6a cable
4K, upto 90 meters over Cat5e cable
1080p, upto 100 meters over Cat5e cable

Class D supports:
1080p, upto 30 meters over Cat6a cable

Class E supports:
4K, upto 1 Kilometer over multi-mode fiber
4K, upto 10 Kilometers over single mode fiber