The Protégé SG is extremely user-friendly with simple one-button activation, adjustable alarm settings and an easy-to-read display.Additional features include data logging and a customizable LCD display capable of displaying real-time gas readings and universal icons for global use. Replaceable lithium batteries provide unlimited life. The Protégé SG performs self diagnostics at start up and is available in the following sensor options HCN, H2S, CO, O2, O3, HCN, NO, NO2, PH3, SO2, NH3, CL2, CLO2.