Been all thru them a lifetime ago during the CTF Flight Test Program ;)...almost mistakenly got locked in prior to launch when doing some checks in the cockpit before a mission.

This is called the UARRSI (Universal Aerial Refueling Receptacle Slipway Installation)...it is essentially the same mechanism used on most military platforms to provision for inflight refueling. The B2 adds a “twist” to the installation to maintain it’s LO characteristics.