Meet IEC 60942:2018, class 2 standard  Stay accurate even in extreme humidity condition  Suitable for all sound level meters with microphone head mechanical compliant with IEC 61094-1 or IEC 61094-4 in a 1/2"(13.2mm) microphone size  Calibration frequency at 1K Hz with three level 114dB, 94dB and 104dB  Vivid LED display with stability and low power indicator  Battery powered, easy to carry around Complete Set Includes:  1 x Sound Level calibrator  2 x AA battery  English instruction manual  Standard Factory Packaging  Calibration frequency: 1000Hz  Frequency accuracy: ±1.7%  Sound Pressure Level: 94dB / 104dB / 114dB  Sound Pressure accuracy: ±0.4dB  Microphone head cavity diameter: 13.2mm (½")  Stabilization time: 10 seconds  Total distortion: <3%  Ambient Condition Influence: Temperature and humidity influence: <0.4dB @ 0...40°C and 25...90%RH Static pressure influence: <0.1dB @65...108kPa  Stability levels Short term stability (<60s): ±0.15dB Stability after 1 year with normal use: ±0.35dB  LED indicator: 1 green/Red: ready/low power; 3 green: 114/101/94dB  Operating Environment: 0~40°C; 25~90%RH  Storage Environment: -20~50°C; <90%RH  Dimension: 60 x 130 x 37.5mm  Weight: ~400gms  Battery: 2 x AA Alkaline battery