Stack Wideband Air - Fuel Ratio (Lambda) gauges are the ultimate tuning aid Dimmable dual digital red numeric and multi - colour radial LED displays provide accurate real - time readout of either airfuel ratio or lambda (user - selectable) in a format that is optimised for driver viewing. User adjustable scaling allows for tailored calibration for specialty fuel types and maximum display resolution per application. Inbuilt peak lean value recall and user programmable alarm setting enable quick data review and driver alerts. Inboard photo sensor provides automatic display intensity adjustment for varying ambient lighting conditions (manual driver control may be enabled via switch connection to the illumination wire on the loom). 0 - 5Volt analogue and serial data outputs may be connected to a data - logger, ECU or other device to provide real - time closed - loop feedback for improved mapping. Pro - Control output allows automatic control of other power systems based on specific Lambda conditions. Supplied complete with wiring harness and includes Bosch LSU4.9 sensor.