The M-159 Tremolo is basically a Dunlop TS-1 in a smaller, pedalboard-friendly chassis. The power supply arrangements aren't quite so friendly: you'll need two 9v batteries or an 18v supply. Like the Carbon Copy it's finished with metallic enamel, plus classy metal T-type knobs.
Controls include the usual Depth and Speed, plus a Shape control. Counterclockwise, the waveform that modulates the volume is a sine wave; this transforms into a trapezoid wave in the centre, and a square wave fully clockwise. It won't change the sound, particularly at high Speed settings, but it does change the feel.
Stereo in/stereo out tremolo pedals are rare. Stereo out might be useful for running two amps, but it's hard to see the full benefit of a stereo input. Maybe it could be placed after a stereo effect on your pedalboard (or maybe your keyboard player will like the idea, and steal it). Conveniently you can use TRS cables for the stereo input and output, but this pedal works in mono too.
There's a second footswitch labelled Pan. In default mode the modulation from both outputs is in sync, but when you activate Pan the modulation ping-pongs between the outputs with an LED that flashes alternately red and green.