Are transducers a universal fit for fish finders?

[nationm]

I'm curious if I were to buy a used fish finder off Ebay that didn't come with a transducer would I need to buy the matching brand specific transducer or are they universal for the most part?

[paxpress]

You would need to get the transducer that is made for your brand/model of unit you purchase.   As an example, some Lowrance/Eagle units use the same transducer.  But a transducer for a Humminbird won't work on a Lowrance.  And just because it's for a Lowrance doesn't mean it fits ALL Lowrance models.   Check with the manufacturer of the unit for the transducer you need.