It's a solid waterproof unit that uses sonar to detect fish, water depth, temperature and underwater terrain detail and sends the data back to your smartphone via the dedicated APP.
The dronar automatically comes on in the water and the battery is capable of up to 5 hours of continuous use and a range of up to 1 mile if connected to the SD4.
The FFD comes with plenty of line so you can hook it up straight to your drone or fishing rod. For more information please see the FFD product page here.
Also coming to the splashdrone 4 fishing add ons is the BR1-S Bait release. This allows fishermen to fill the payload container with bait and drop it to a specific area to improve catch rate (use your FFD to find the best area first!)