Two types of alarms - one audible and one visual - alert user to either a low battery 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: M-307 Respiratory Hard Hat Assembly, TR-302N+ PAPR Unit, TR-326 High Durability Belt, TR-341N Battery Charger, TR-3712N Filter, TR-362 Spark Arrestor, TR-3600 Pre-Filter, TR-332 High Capacity Battery, BT-30 Length Adjusting Breathing Tube, TR-971 Airflow Indicator.Inspection Cleaning and Storage Procedures for 3M™ Versaflo™ TR-300+ PAPR Assemblies Tech Bulletin