Didn't the guage come with an oxygen sensor? Check the manual and get whatever one that it recommends.
Or is it one of those guages that connects to your stock oxygen sensor? If so, return it. It is a narrow band guage. When trying to monitor your AFR, you really need a wideband oxygen sensor/guage. You can't just connect a wideband sensor to a narrow band guage. The readings would be useless.
I'm personally saving up for the
AEM UEGO. It is a very good looking compact unit. It also has a 1 volt output so that you can use it's oxygen sensor in the stock location.
Others like the
Innovate guage/sensor.
BTW, I think that most of the aftermarket AFR meters use a Bosch sensor.
HTH,
BP