The GX-3R Pro is the worlds smallest 5 gas monitor weighing only 129 grams and fits in the palm of your hand (73 W x 65 H x 26 D mm). It simultaneously monitors and displays up to 5 different gases. In addition to monitoring standard confined space gases, LEL, O2, CO & H2S, the GX-3R Pro has a 5th channel where you can add ppm or % volume CO2, or SO2. A H2 compensated carbon monoxide sensor is also available. Two of the four sensor slots have interchangeable sensors providing flexible configurations.