The main arm includes five electrical motors and five joints, known as the shoulder azimuth joint, shoulder elevation joint, elbow joint, wrist joint and turret joint.
Measuring 2.1 meters long, the arm will allow the rover to work as a human geologist by holding and using science tools with its turret, according to JPL.
"You have to give a hand to our rover arm installation team," said Ryan van Schilifgaarde, a support engineer at JPL for Mars 2020 assembly. "They made an extremely intricate operation look easy. We're looking forward to more of the same when the arm will receive its turret in the next few weeks."
The rover's turret will include high-definition cameras, science instruments, and a percussive drill and coring mechanism. Those tools will be used to analyze and collect samples of Martian rock and soil, which will be cached on the surface for return to Earth by a future mission, said JPL.
Mars 2020 is scheduled to launch from Cape Canaveral Air Force Station in Florida in July 2020, and land at Jezero Crater on Mars on Feb. 18, 2021.