Gain Express Landtek Instruments Professional Digital Sound Level Meter 30 to 130db with Bluetooth Standardisation: IEC651 Type 2, ANSI S1. 4 Type 2 ; PC interface: Bluetooth + CD Software Support WIN 8 ; Function: Lp, Leq, Lmax, LN. with Frequency range: 20.0 to 12,500Hz Frequency range: 20.0 to 12,500Hz / Frequency weighting: A, C and F (Flat) Alarm: electron, adjusable, 30-130dB set, LED and optional relay contact (NC) output Built-in calibration signals: 94dB at 1kHz (sinusoidal)