Thats SE Sport High Performance Hydrofoil. Its a stabilizer basically....it allows me to run slow without my bow sticking up in the air so I can see better....It also makes for a better hole shot and helps me get on plane quicker, and it really helps stabilize and control the boat in tight high speed turns. It also helps prevent cavitation and it will also help you save fuel. I have had one on every boat that I ever had. I like them.