MULTIGAS DETECTION: This replacement XCell sensor is specifically designed for two-tox detection of carbon monoxide (CO) and hydrogen sulfide (H2S). Altair 4X is equipped to measure up to four gases in one device, designed for virtually no cross-channel interference FULL-TIME TRACEABILITY: Records 500+ alarm events and 50+ hours of data (including bump and calibration records), rechargeable Li-polymer battery with 24-hour run-time SAFETY & COMPLIANCE: LED indicates bump pass/fail with large on-screen cues, equipped with MotionAlert (man-down alarm) Feature, InstantAlert (manual alarm) Feature, and end-of-sensor-life warning RUGGED DURABILITY: Tough over-molded rubber armor, survives multiple 25-ft drops onto concrete, MIL-STD-810G drop protection, certified IP68 rating, dust and waterproof COMPREHENSIVE EQUIPMENT: Includes detector, performance guarantee, 4-year warranty, Bluetooth connectivity capabilities, and MSA ALTAIR Connect App access