eSATAp (also known as Power over eSATA, Power eSATA, eSATA/USB Combo, eSATA USB Hybrid Port (EUHP)) is a combination connection for external storage devices. An eSATA or USB device can be plugged into an eSATAp port. The socket has keyed cutouts for both types of device to ensure that a connector can only be plugged in the right way.
There are two versions of this port. Most laptop computers do not have +12V power available, and have an eSATAp port which provides only +5 V. Desktop computers, with +12V available, have a port with two additional pads, placed against the plug's horns, which provide +12 V. Some manufacturers refer to these ports as eSATApd, where d stands for dual voltage. Some devices, such as 2.5-inch drives, can operate off the +5V supplied by laptop eSATAp ports. Others, such as 3.5-inch drives, also require +12V; they can be powered from a desktop eSATAp port, but require an external +12V power supply if used with a laptop computer. This can lead to confusion if users are not aware of the distinction.