Mm

mm
An abreviation of millimetre. milli is the prefix representing a multiplication of 10-3 and metre is the SI unit of length.
MMC
Abbreviation of Metal Matrix Composite.
MMCF
Symbol for one million cubic feet.
MMcfe
Abbreviation of Million Cubic Feet Equivalent.
mmHg
When measuring pressure using a mercury barometer it is normally expressed in mmHg, Hg being the chemical symbol of mercury.