Loud 90 dB horn Battery status indicator Real-time clock Hydrophobic filter Dust inhibiting particulate filter (inside inlet) LED alarm indicator Voice Assist speaker, with four language options User selectable internal sampling pump/diffusion Multi-use port (charger, data logging) Field interchangeable NiMH or alkaline batteries Interchangeable plug-in sensors Simple one-button operation 4-line automatic backlit display Easy calibration Non-intrusive battery compartment Rugged RFI/EMI resistant aluminum case