Two types of alarms - one audible and one visual - alert user to either a low batter or low flow, such a when a particle filter is fully loaded. LED lights on the battery indicate its charge status on and off the charger. The kit includes: S-133S Headcover, BT-30 Length Adjusting Breathing Tube with BT-922 Breathing Tube Cover, TR-302N+ PAPR Unit, TR-327 Easy Clean Belt, TR-332 High Capacity Battery, TR-341N Battery Charger Kit, TR-3712N HE Filter, TR-3600 Prefilter, TR-971 Airflow Indicator.