All depth finders have to have a transducer to locate the bottom, structure, and fish. If you are looking at one and it says CHO, that means that you are only getting the headunit for that price. Look down in the specs. and it will tell you what type transducer you are getting. Dual beam 200/50, or single beam 200. Types of transducers vary. The larger the number the more detailed or smaller the cone. The smaller the number the bigger area you can see with less detail.
Guys make sure I explained that narrow wide/ wide beam thing correctly. That confuses me to this day.
Hope this helps,
The Hound