The ACI Platinum Immersion Series features a stainless steel probe with Etched Teflon colored lead wires to differentiate the different sensor types. The three‑wire "‑3W" option should be ordered when using with a 3‑Wire temperature transmitter or sensor configuration on your building management system or PLC (Programmable Logic Controller). The purpose of the 3rd wire is to compensate for external lead wire resistance that affects the sensor output. ACI recommends the use of 18 AWG lead wires to reduce the external lead wire resistance when using a Platinum RTD. The sensors in this series are manufactured using ACI's proven double encapsulation process to eliminate the effects of moisture upon the sensors and to increase thermal response times using our high quality, thermally conductive epoxy. The immersion sensors "‑I" include a welded thermowell but can be ordered without the thermowell "‑INW" version. The "‑INW" includes a standard 1/2" NPS process thread to be used with an optional machined thermowell or an existing thermowell application. Optional NEMA/IP rated weather proof enclosures and NIST Certificates are available as referenced on the back of the product data sheet.