SUPERIOR SENSORS: Fast-responding 20 Series oxygen and toxic sensors, detector meets UL/cUL/ATEX/Australian standards, sensors simply plug into internal circuit board for fast, easy replacement. DATA LOGGING: Unit automatically records 50 latest events in the session log, records peak gas readings or low O2 readings every three minutes in a periodic data log. SAFETY & COMPLIANCE: Distinctive triple-alarm system, alarms are indicated by flashing LEDs, audible alarm and internal vibrating alarm, one-button operation. DEPENDABLE DURABILITY: Small rugged design, tough rubberized housing, excellent impact resistance, dust and water protection, IP67 rating (except with O2-R). EASY TO USE: 1-button gloved hand use, large backlit LCD, care and use instructions included, runs on a single simple-to-install CR2 camera battery, customize through MSA FiveStar Link software.