Product Description Replacement electrochemical Hydrogen Cyanide sensor for the Ventis® Pro. The HCN sensor has a measuring range of 0-30ppm with a .1ppm resolution. 6 series sensors can be installed in locations 3 or 4 of the Ventis Pro. (This sensor will not fit or work with Ventis MX4 Series Gas Monitors)Has your HCN sensor failed or has a measuring range that's all over the place? It might be time to replace it. Repair your Industrial Scientific Ventis Pro Multi-Gas monitor by purchasing a new genuine Industrial Scientific (HCN) Hydrogen Cyanide Sensor.Need some DIY help changing a sensor or just some friendly technical help with repairing your instrument? Call customer service at 1-800-949-7233.