The CM-4 is a quite simple fully manual SLR from Chinon.
The light metering display is just 3 LED's: a green one for correct exposure, and two red ones which indicate over- or under-exposure. These LED's are placed outside the viewfinder, but it is possible to see them while focusing. Choosing either a different aperture or shutter speed will have an instant effect on the LED's. Shutter speeds go up to 1/1000.
This model accepts all all Pentax K mount lenses. It's commonly seen with a CHinton 50mm f/1.9 standard lens which gets quite good reviews.
The LED metering circuit is powered by two LR44 or SR44 batteries. A curious feature is a front-facing red LED "Action Lamp" which blinks while the shutter is open. The Chinon CM-4s adds a self-timer, which replaces the LED.