The GM70 handheld carbon dioxide meter fromVaisala Inc. (Woburn, MA) measures carbon dioxide from low concentrations (0 to 2,000 ppm) to high (up to 20%) concentrations of CO2. Features of the unit include the uses of the silicon-based Carbocap(r) sensor, a menu-based user interface, and clear graphical backlit LCD, and optional Windows(r) software.