BW Clip BWC2-M CO Single Gas Detector with a 2 Year Warranty is your everyday companion for hazardous environments. It operates up to three years maintenance-free: Just turn on the device and it runs continuously — no need for calibration, sensor replacement, battery replacement or battery charging. That means great reliability and no downtime.  for CO, you can put the device in a hibernation case when you’re not using it for a week or more — and extend its life by that period of time