If you have an older 840, this is the least expensive way to buy the X4 Probe and LCD Display to use with your existing power cord and transducer.

PAK Includes the X4 Display and X4 Probe. The Fish Hawk X4 offers double the performance and uses the same transducer as the 840 – meaning you don’t need to re-wire anything on the boat, the X4 plugs right in!