This is one half of the RambleBot single servo gripper, it matches the outer side also found in our shapeways shop.
Designed to be a simple and functional as possible it is put together with basic zip ties and any standard sized micro servo. No glue required make repairs and replacements dead simple. By adjusting the shaft bolt tension onto the robot arm you are able to change the vertical axis of the gripper by simple draging it forward or backward on the ground.
The cheapest most functional single servo gripper available.