FLIR Digital Sound Level Meter with NIST 

This FLIR Digital Sound Level Meter with NIST  is ideal for conducting noise surveys. It features a digital display with a fast reacting analog-style bar graph. With a 40 to 130 dB range, and a 2 dB accuracy, you can choose from A or C weighting, and the Max Hold function captures the highest reading so you can walk through an environment without having to gaze at the display. This is the NIST version, which means the unit has been calibrated by the National Institute of Standards and Technology and includes a certificate and documentation.