I am selling a Shadow Hills Mono Optograph. This is a compressor in the API 500 series format. It's a discontinued product, so it's rare to find it on the used market. I purchased it used last year and have been using it in a non-smoking, pet-free recording studio, and it has not been taken outside. I have confirmed all basic operations for this listing. There was some crackling when switching switches, but I don't think there are any particular problems during normal use. I have confirmed that all controls are working, but please note that I have not performed precise measurements. The VU meter has been slightly loose since I purchased it. The screws don't tighten, but there haven't been any problems, so I've been using it as is. The only item for sale is the main unit; there are no other accessories. Please note that this listing may be canceled suddenly, as it is also listed on other sites.