For Extech SL130G Sound Level Monitor The SL125 is for use with Extech’s SL130G Sound Level Monitor. Extends microphone up to 15ft (5m) for remote operation.From noisy nightclubs to loud manufacturing facilities, Extech decibel meters are used around the world to test whether a sound level exceeds levels established by municipal or national laws. Occupational safety and health standards turn to Extech for a reliable sound meter (commonly called a dB meter or noise meter) to determine an acceptable noise level with and without hearing protection. For on-the-person occupational sound measurement, Extech’s noise dosimeter selection offers options for datalogging personal exposure to excessive sound levels.