The RKI 03 Series pocket-sized single gas monitor for LEL, CO, H₂S, or O₂ detection. O₂, CO, and H₂S versions operate 3000+ hours on two AAA alkaline batteries; LEL version operates 35 hours on alkaline or 30 hours on rechargeable Ni-MH.

Features include peak hold, low battery, STEL, and TWA alarms with audible, visual, and vibration alerts. Automatic backlight for low-light conditions. IP67 impact and water resistant. Intrinsically safe with ATEX/IECEx and CSA approvals for Class I, Division 1, Groups A-D. LEL and O₂: 2-year warranty; H₂S and CO: 3-year warranty.