Mass. Gen. Laws ch. 90, § 34C

Any person applying for the registration of more than one motor vehicle under section two or three, or any manufacturer or dealer or repairman applying for registration of motor vehicles under section five, may, in lieu of procuring a separate policy or bond covering each motor vehicle, furnish a single motor vehicle liability policy or bond covering all motor vehicles owned or controlled by him, in which the amounts or limits of indemnity as provided in section thirty-four A for a motor vehicle liability policy or bond shall apply to each motor vehicle covered thereunder.