The ball sizes and the weight capacities are different. Go to the Ram Mount website and do some research. They have a page where you can put in a specific model FF and it will tell you the recommended mount.
2015 Seaark 1872 MV CC Etec-90
Two Helix 12 CHIRP SI's, , MinnKota Riptide ST80/i-pilot Link, Bob's Hydraulic
Bitter Gun Owner