the zeitronix zt-2 that i have has a O2 sensor that has a large plug on the end. about 12" long cable. that plug goes into another plug that plugs into the zeitronix controller. that way if the O2 sensor ever goes bad you simply remove it from the bung unplug it and get another from zeitronix.

heres a couple pics for you. see how the O2 sensor goes into the zt-2 box with what looks like a fone jack. its about 6 ft long.from the zt-2 another smaller plug goes out and into the dashdaq. plug and play!