2" Rudder Angle Indicator - Chesapeake White with Stainless Steel BezelFaria Beede marine gauges designed to measure the angle position of boat rudders. These gauges use single or dual rudder angle indicators as a sender to give a visual display of rudder position to a gauge mounted in the boat dashboard. The senders work by measuring the angle of the rudder or rudders and converting that to a level, where 180 ohms equals starboard, 95 ohms is the mid point, and 10 ohms displays port on the rudder indicator.Hole Size: 2 inches in diameter