This is one of the early handheld GPS units, the Garmin GPS 75. I bought it somewhere around 1993. It only tracks 8 satellites while some of the new units will track twice that many. It still works although it is very slow to lock onto a sufficient number of satellites to give you a position. It has helped me many times over the years to find my way back to port from a position in the Great Lakes where you can no longer see landmarks with the eye.