The Sper Scientific Sound Level Pen features a type 2 internal calibrator, one-button operation, low cost, auto-ranging and max hold in a mini size. The Sper Scientific Sound Level Pen is the smallest, lightest, easiest to carry sound meter in the world. Despite its small size, the Sound Level Pen is a full function type 2¹ sound meter perfect for testing OSHA requirements and most other sound meter applications. Auto-ranging with simple one-button operation. Press once to begin reading sound levels. Press the button a second time and the display holds the maximum reading, updating as new maximums are reached. Hold the button for 2 seconds to turn the unit off. Measures the 32 ~ 130 dB range in the "A" scale, with an accuracy of ±1.5 dB. The display provides 0.1 dB resolution, under range, over range and low battery indicators. The Sound Level Pen calibrates electronically to its own internal oscillator² or external 2 Pt. Acoustical Calibrator 850016. Comes ready to use with two AAA batteries, instructions, calibration tool, and a wind screen. N.I.S.T. traceable certificate of calibration available.