I have the display instrument for a Datamarine knotmeter (which also records trio distance). I also have a Datamarine A-181 log control panel, which records trip and total distance. It comes with a little plywood mounting box that you can use or not. The knot meter has a little wear on it (cosmetic) and was working when I took it out of the boat. The log is in beautiful condition.
Included is the cable that links the two of them. You will need your own transducer, but the DMI website can get you the specs for that - there are a few suppliers that have standard transducers that will work.