The Galaxy Audio CM-140 Check Mate Sound Pressure Level Meter is a small, handheld device that measures the pressure level of sound waves in any acoustic environment. For audio enthusiasts and sound recording engineers, this is a must. The CM-140 meter gives you objective, accurate measurements of SPL, and it's easy to usel. The CM-140 features an electret condenser microphone, MAX/MIN function, level range display, AC signal output, and readings in 0.1dB steps. Frequency range is 31.5Hz to 8KHz. You get up to 70 hours of operation from one 9V battery. Galaxy Audio includes a manual, a 9V battery, and a windscreen with the CM-140 Check Mate SPL Meter.