GRF™ 10 - Rudder Feedback Sensor. Compatible Devices: Pair this sensor with the GHP 12™ to provide rudder position feedback and to detect and avoid rudder stops while sailing or boating. The GRF 10 uses a magnetic sensor to relay position information, eliminating friction that causes other types of sensors to wear out. The arm of the GRF 10 is connected to the rudder of the boat and relays position information through the sensor to the mariner so they know where the rudder is - giving them an added peace of mind when starting from a stopped position, docking, launching or moving at slow speeds. Additionally, the GRF 10, allows sailors to: Know where the rudder is positioned without having to look back, Make smoother maneuvers and avoid over-compensating, Save undue wear and stress on their autopilot system by eliminating force on the rudder when it's already stopped left or right.