Two night vision monocles are missing from the Army Reserve's 672nd Engineering Company in Missoula.
The Missoula County Sheriff's Department said the monocles are valued at $3,600 apiece.
Investigators said the devices were scheduled to be shipped to another facility.
"There were 13 of them that were scheduled to be sent to another facility," said Missoula County Sheriff's deputy Paige Pavalone, "and when they went into inventory them before they got shipped off, they realized that two of the monocles had been removed from their original casing."
The Sheriff's Department said the monocles are used by military and law enforcement tactical teams. They are common tools of Missoula's SWAT team.