An E-Mek is a mechanical suit of armor employed by the elf army.
After exiting a bar and finding a pilot, Emily and crew encounters E-Mek Five that is being piloted by a rather diminutive elf. The elf seems to pay no regard to his surroundings and launches a barrage of gunfire at the gang. When they enter an airship, the elf switches to missiles and attempts to detonate the aircraft, but they manage to outmaneuver them. Also, 4 other E-Meks (maybe E-Meks 1, 2, 3, 4?) guarded the hangar of the Elf battleship in book 6.
The vehicle is very bulky and is made of a typical metallic material. In its center, a rectangular opening allows the pilot visibility, while large arms on each side of the mech's face employ machine guns. Many of its features appear to be voice-activated.
The machine guns can toggle between firing bullets and missiles. In addition, the armor's large size can deal a heavy amount of damage on its own.