Ultra-2 (sometimes spelled "Ultra2") uses a 40MHz clock rate to get maximum data transfer rates up to 80 MBps. It provides a longer possible cabling distance (up to 25 meters) by using Low Voltage Differential (LVD) signaling. Earlier forms of SCSI use a single wire that ends in a terminator with a ground. Ultra-2 SCSI sends the signal over two wires with the data represented as the difference in voltage between the two wires. This allows support for longer cables. A low voltage differential reduces power requirements and manufacturing costs.