Launched respectively in 1989 (GDM 400) and in 1992 (GDM 500), these total stations decreed new standards for surveying tools.
- Different angle accuracies based on the models
- Servo-assisted (400 series only)
- Numeric or alphanumeric keypad
- Electronic spirit level, which eliminates the need to rotate the instrument during the initial leveling
- Coaxial optic (500 series only)
- Bidirectional data download (500 series only)