This Power Over eSATA to SATA 22pin cable enables you to connect your 2,5 or 3,5 SATA HDD externally to any free Power Over eSATA (eSATAp) port. This Power Over eSATA port combines eSATA and USB and enables, by help of the two gold contacts, a power supply of 12V.Thus you do not require any additional power supply for a 2,5 or 3,5 HDD. The cable can also be connected to a 5V eSATAp port, so that you will get only the required 5V for running your 2,5 HDD.