Basic Omni Bearing Indicator, like this Bendix-King model, has a manually operated radial or 'omni bearing' selector [OBS] which rotates an azimuth ring marked from 0° to 355°. The OBS selected radial is indicated by the arrow at top dead centre and the reciprocal bearing is indicated by the bottom arrow. The other features of a basic OBI are the TO–FROM indicators, a deviation bar, a deviation indicator needle and a NAV/OFF alarm flag.