The UNI 321 is a disposable, maintenance-free version of the UNI single gas monitor. It detects hydrogen sulfide (H2S), carbon monoxide (CO) or oxygen (O2) in your selection of models for an operating life of either 12 months (MP101), 24 months (MP102) or 36 months (MP103). The detectors have a large LCD providing maximum readability in the field. Six bright red LEDs allow for quick alarm notification. Constructed of strong and durable material, the UNI 321 is designed to be comfortable yet drop-resistant. The UNI 321 series can easily be bump tested and calibrated either manually or using the convenient Single Docking Box, or CaliCase for up to 4 units at a time.