Power plug on Tug Hercules at Hide Street Pier, San Francisco. Mates with <a href="//commons.wikimedia.org/wiki/File:Power_socket_Hercules.jpg" title="File:Power socket Hercules.jpg">File:Power socket Hercules.jpg</a>
<a href="//commons.wikimedia.org/wiki/User:ArnoldReinhold" title="User:ArnoldReinhold">ArnoldReinhold</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>