The Borei class, alternate transliteration Borey, Russian designation Project 955 Borei and Project 955A Borei-A (Russian: Борей, lit. 'Boreas,' NATO reporting name Dolgorukiy), are a series of nuclear-powered ballistic missile submarines being constructed by Sevmash for the Russian Navy. The class is projected to replace the Soviet-era Delta III, Delta IV, and Typhoon classes in the Russian Navy service. Despite being a replacement for many types of SSBNs, Borei-class submarines are much smaller than those of the Typhoon class in volume and crew (24,000 tons opposed to 48,000 tons and 107 personnel as opposed to 160 for the Typhoons). In terms of class, they are more accurately a follow-on for the Delta IV-class SSBNs.