Click the picture for more details. Octura stepdown propeller shaft, 3/16" (4.75mm) to 1/8" (3.175mm). The shaft is drilled to fit a .130 flex cable. Designed to use smaller 1/8" props with a stronger 3/16" shaft and .130" flex cable.Fits struts that require a 3/16" propeller shaft. Requires: .130 Flex Cable Part# oct-oc4d Drive DogPart# oct-oc4pn Bullet Prop Nut