This product is new in the box. It's only ever been opened to take pictures. I started building my car and decided to go a different route. I paid about $390(shipped) for it a few months ago.

The Zeitronix Ethanol Content Analyzer display provides real time readouts of fuel ethanol content and fuel temperature.  The Zeitronix ECA features a slim aluminum case and blue LEDs to create a bright, easy to read, surface mountable display.   Two analog outputs, ethanol percentage and fuel temperature, are provided for datalogging and engine management system use.  A flex fuel sensor (GM part number 12568450 or 12570260) is required.  Production vehicles including ones with the flex fuel insignia or which can run on E85 have flex fuel sensors.  The sensor can also be purchased separately at GM dealerships and installs as part of the fuel line.  The Zeitronix ECA connects via one wire to the sensor providing a real-time look at fuel mixture being sent to the engine.

Specifications

Displays fuel ethanol content from 0% to 100%

Displays fuel temperature in Fahrenheit and Celsius ranging from -40 to 125 F (-40 to 52 Celsius)

Two analog outputs: Ethanol % and Fuel Temperature for use with logging or engine management systems

Sleek aluminum enclosure with bright LED display visible even in direct sunlight

Compatible with standard OEM sensors used in most flex fuel vehicles (GM part number 12568450 or 12570260)

Dimensions: 2.8 x 1.8 x 0.75 inches (71 x 46 x 19 mm)

Made in the USA!