The USB485-HS converts the short range USB output of the computer into the industry standard, long range RS485 protocol. It is used to communicate between the PC and LOR light controllers. Only one USB485-HS is used to operate an entire network of LOR controllers.
The USB485-HS is the choice when you plan to use the highest speed (500K) for your LOR network. The other LOR USB adapters were designed for speeds of 250K or less. However they appear to work well at 500K so if you have a working 500K network using one of the other USB adapters there is no need to change. The USB485-HS is designed to work at 500K speeds.