1980s Heathkit M1-2901 fish spotter / finder, vintage fishing equipment

Heathkit model M1-2901 Deluxe Dual Range Fish Spotter. This offered for sale in Heathkit's Spring 1984 catalog as a kit for $139.95. This fish finder is marked for two 6 volt lantern batteries, but has been wired with two small cable clamps (red and black, like you see on automotive power inverters to allow you to hook them up to your truck battery. This was probably done to allow it to be hooked to a deep-charge marine battery onboard the fishing boat for longer run or because the owner couldn't easily get the 6 volt batteries.

This looks in good condition.