The design consists of the M298 cannon, M191 bipod, M9 baseplate, and the carrier adaptation kit. With the use of an auxiliary M9 baseplate and extension feet for the M191 bipod, the M121 can be dismounted from the vehicle and emplaced for ground-mounted operations.[citation needed]
The first M1064s were converted from M106 mortar carriers, whose 107 mm mortars had been replaced by the 120 mm mortars.[1]