The Dualsky FPS-Z spinners are manufactured with excellent craftsmanship, using quality materials. They feature an alloy offset "Z" yoke to get your blades folded in super close and ultra strong, hollow stainless steel blade retention pins. The cone can be used closed or mounted with an included smaller screw to expose a built in cooling air inlet, an O-ring is included for active propeller folding too. For optimum performance, use with Dualsky Dragonfly or Dualsky DFP Classic propellers.