4x WB-O2 Nano Harness allows you to connect up to four New WB-O2 Nano Wideband O2 Controllers and WB-O2 Nano (V1) Designed for seamless integration, this harness streamlines wiring, enabling accurate data collection across multiple wideband sensors. Perfect for tuning and monitoring closed loop systems with 1 O2 sensor per cylinder, the 4x WB-O2 Nano Harness maximizes efficiency and simplifies installation.
Length: 6.5 ft. 
For more information - How to Install a FuelTech WB-O2 Nano Wideband O2 Sensor Controller