ALIENS Motion Tracker Replica. In the 1986 movie Aliens, Ripley and a team of marines used the motion tracker to locate and track deadly aliens on their mission to save any remaining survivors of a human colony. This life-size motion tracker replica has a blinking display screen that simulates the radar effect seen on screen. The sonar pulse sound and warning pings simulate the sound effects used in the movie when aliens were detected by the device. The Humbrol "Brown Bess" (brownish green) finish faithfully replicates the look of the prop seen in the movie. The custom designed display case has a black base and acrylic dust cover. This replica was designed utilizing close examination of hundreds of stills from the movie. This replica measures 9-inches x 7-inches x 11.5-inches.