The Moki 180 is a little more complex than most. The threaded portion of the shaft is 10x1mm. Part of the shaft, closest to the prop washer, is not threaded and is 12mm. The length of the 12mm portion is slightly longer than the thickness of the Tru-Turn spinner backplate. What this means is the prop will have to be reamed to 10mm in front and 12mm in the back. The Moki shaft is also very miserly in length -- there is no extra length to play with normal adapter nuts. The Tru-Turn Adapter nut replaces both the front washer and nut. The nut portion of the adapter recesses inside of the washer, otherwise it would not have much thread on the shaft to work with.