GASMASTER - TXGARD SERIES - Range of 0-10 ppm - The Gasmaster Series of single and multi-channel control units can be connected to the TXgard Series of toxic and oxygen gas remote sensors. The TXgard Series are available in several versions for almost any application. The Gasmaster Series offers digital display, built-in battery back-up, continuous output signals, common and individual dual level alarms, relay contacts, and can be used with most other remote sensors that transmit a 4-20 mA signal.