This powered air-purifying respirator (PAPR) is always used with a high efficiency particulate filter; the HE filter can be “stacked” onto an optional 3M™ Adflo™ Cartridge Filter for additional protection against organic, sulfur dioxide, chlorine, and hydrogen chloride (OV/SD/CL/HC) vapors. The slim profile is designed to go into tight spaces. Environmentally-friendly NiMH battery charges in less than 3 hours with a smart charger that won’t ever overcharge. Audible and visual alarms signal low airflow and low battery charge.