Type F and FH – Stainless-steel Duoprop propellers,for DPS, DPS-A drives (straight splines). This is the perfect upgrade for enhanced performance, strength and durability.This is the perfect upgrade for enhanced performance, strength and durability. It provides better acceleration and higher top speed due to greater strength and thinner blades - versus a comparable aluminum propeller. The high-strength stainless steel adds excellent durability and corrosion resistance. Complete with shock-absorbing rubber bushing and galvanic isolation makes it perfectly matched for the DPS-drive and the ultimate choice for demanding boaters. Type F has straight splines, type FH has helical (spiral) splines.