The meter has an LCD display and measures a wide range of sound levels with slow and fast averaging, peak, impulse and maximum sound levels, linear, A-weighted and C-weighted.  It can use polarized and pre-polarized microphones (not included).  External filters can be added (filters not included).  There are AC and DC signal outputs.  The sound level meter was part of a set of equipment used for recording and analyzing aircraft noise.  It was all calibrated and operational when it was put in storage and has not been used since.  Current operation has been verified by checking sound level readings with the matching microphone and pistonphone.  The Instruction Manual is included.