Application: it is used to calibrate the sound level meters. Model:SL5868P This instrument is compatible with several standards ... Type 2.It is widely used to test the sound level of environment, mechanic, vehicle,ship and other noise.Fit for ... ................1pc. 3.Operation Manual..........1pc. Optional Accessories: 1.ND9 sound level meter calibrator 2.RS-232 and software 3.External rela ...