The "N" variant was developed specifically for the U.S. Navy and is in use by the U.S. Navy SEALs.
The HK MP5N is another variant of the highly successful HK MP5 series of submachine guns. The 'N' designation is reserved for 'Navy' and stands as the Navy Model of the MP5 series which was designed specifically for use by the United States Navy. The 'MP' in the designation refers to 'Machine Pistol'. The Navy Model features the specialized Navy trigger system, threaded barrel, a retractable shoulder stock and fixed front sights made of titanium. The HK MP5N can be fitted with a specially designed stainless steel waterproof silencer.