Extech SL400 Personal Noise Dosimeter with USB Interface Measures frequency weighted noise exposure and peak (C, Z) sound level Datalog's up to 999,999 readings when used as a sound level meter with sampling times between 1 second and 24 hours Sound level mode: displays sound level, min/max, time-averaged sound level (Leq), peak, and sound exposure level (SEL) Adjustable Criterion Level, Exchange Rate and Threshold One user-defined measurement setup