M204 is assigned to 1833, 1837, 1841 and 1845; M555 is a second flag in 1845. The painted M555 has a shallow V in the letter.
Loughran dates Montano to 1829–1869, while Nantucket Signals records sale to California in 1849. Owners included Philip H. Folger, Samuel B. Folger, James Athearn and Frederick C. Sanford. Agents included Samuel B. Folger, Barker & Athearn, and Edward Field.
Keep the explicit scope label independent; no alias or company identity is inferred.