The CM-170 is an affordable IEC 61672-1 Type II SPL meter that competes with some of the best SPL meters on the market. The CHECK MATES are inexpensive tools that everybody working in loud environments should own. Windscreen and protective case are included with the CHECK MATE models. The CHECK MATE series SPL (Sound Pressure Level) meters, first introduced in early 2003, allow musicians, sound contractors and others to measure SPL in decibels (dB). A decibel is defined as the unit for measuring relative loudness of a sound. We have expanded our line from one CHECK MATE SPL Meter to four products in the category. We have sold thousands of units to working musicians, DJs, police departments, sound contractors, racetracks, etc.