This is Hobie part # 30110 Anti pitch pole hydro foils. Designed for the Hobie 16. Sold as a pair, a simple bow plane that attaches to the box tang bolt. As the bow starts to dive the bow plane’s 55 square inches of surface comes in contact with the water and halts the submerging of the bow before the beck goes under water. Easy to install or remove for racing. Makes sailing a lot more fun for the recreational sailor.