In this image, taken on June 21, 2019, engineers at NASA’s Jet Propulsion Laboratory in Pasadena, California, install the main robotic arm on the Mars 2020 rover. (A smaller arm to handle Mars samples will be installed inside the rover as well.) 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 7 feet (2.1 meters) long, the arm will allow the rover to work as a human geologist would: by holding and using science tools with its turret, which is essentially its “hand.”
Source:
https://phys.org/news/2019-07-image-mars-rover-seven-foot-long-robotic.html