The Navy awarded Britain’s BAE Systems A $47 million contract option to deliver four more Mk 45 5-inch naval guns, upgrading existing units, the company said Jan. 22.

This is a modification to an initial 10-gun contract that will now upgrade four existing Mk 45 guns to the Mod 4 configuration, which will increase their range and firepower.

Mk 45s are installed aboard Arleigh Burke-class DDG-51 guided-missile destroyers and Ticonderoga-class CG-47 guided-missile cruisers.

This modification increases the total contract value to $177 million for 14 total guns.

BAE said work will start immediately with the first delivery expected in 2020 and total work set to be complete by 2021.

The Mod 4 changes include strengthening the structure of the gun mount and more advanced electronics. The improved mount allows the gun to reach a 50 percent higher firing energy, translating into munitions traveling faster and longer ranges, the company said.

The new guns also come with a digitized control system that provides greater computing power and a touch-screen user interface.

“The Mk 45 is the industry standard for large caliber naval guns, and the Mod 4 updates make the system easier to integrate onto the ship and more adaptable to advanced munitions,” Joseph Senftle, BAE’s vice president and general manager of weapon systems, said in a statement.

The company underscored it expects the gun to stay in serve for decades and the conversion increases the gun’s adaptability for advanced munitions under development.

BAE will conduct the contract work at its Louisville, Ky., facility.

The upgraded Mk 45 guns are expected to remain in service for decades to come. The Mod 4 conversion helps increase their adaptability for advanced munitions that are under development and are considered an essential component of future surface warfare.