Military Shuttle 12091 was a Bardeen-type shuttlecraft used by Starfleet during the late 2250s of the alternate reality.
In 2258, this shuttle was in Hangar 1 as Starfleet Academy cadets were ferried to starships waiting at Starbase 1. Spock and his counterpart from another reality later had a chance encounter near this shuttle following the destruction of the Narada. (Star Trek)
The designation of "Military Shuttle" comes from the shuttle's wall accents, which reads "UFP MIL-SHUT-12091".