GMA 80A Series Controllers are used to control and evaluate remote GfG gas sensor transmitters, creating a safe, reliable and cost-effective fixed single channel or multichannel gas detection system with transmitters available to detect and measure over 500 different combustible and toxic gases and oxygen. Combine the GMA 81A with a single transmitter, the GMA 84A with up to four transmitters of the same sensor type and range, or the GMA 88A with up to eight transmitters of the same sensor type and range, or two groups of four similar transmitters.