i had two ofthese. thy work just fine as reflection and transmission densitometrs. they were sold as part of an agfa stat camerafor pre-press work. for transmission measurements you need a light source such as a ligh table for reflection he built-in light source is all that is needed. just aim the target in the foot stand ,push the head down and read the density off the led dsplay. my experience was that they are very accurate and repeatable. godd catch for that money. i sold mine for 100 gbp each!