Flights to St. Thomas and St. John. Enjoy a magnificent trip to St. Thomas and St. John, two islands that promise to provide a seaside paradise for you to revel in throughout your vacation.
A Relay Rack is a 2-post aluminum or steel structure with either EIA standard (round) mounting holes or universal (square) mounting holes. Relay Racks are also known as 2-Post Racks or Open Bay Racks. The vertical holes spacing on Relay Racks are standardized for mounting Telco, or computer / network equipment.
  A relay takes a high current circuit and uses low current to turn  the high current on and off. Its basically a high current switch.  There are coils that are designed to handle the high currents  constantly. A switch could do the job of turning circuits on and  off but has a drastic higher failure rate.  The reason for using a relay, is so that you can power a load that  requires a lot of current, without having to run heavy cable all  the way to the switch and back. Also, for safety, so you don't have  to throw the switch on a potentially lethal amount of current.