What new piece of military tech cost us taxpayers around £1 billion but packs a sonar powerful enough to detect ships 3,000 nautical miles and cruise missiles with a range of 1,240 miles?
That would be the Royal Navy's latest Astute Class submarine, the HMS Artful which was lowered into the water this weekend. It is one of seven nuclear submarines being built by BAE Systems.
Stuart Godden, Astute programme director for BAE Systems, said: "Moving a submarine of this size from its build hall to the water is very challenging.
"It's testament to the experience and careful planning of the team involved that Artful is now ready for the next phase in her programme.
“Witnessing a submarine move out of the hall and be readied for launch is truly inspiring and a source of great pride to the thousands who have played a part in getting Artful to this stage.”