The L/H pic is the Tru-Turn Part number 0125A nut right after I finished grinding the nut flats off to 1/2 inch diameter. The stock washer is left of the nut. The middle pic shows the stock washer mounted in its groove. The right pic has the 1/2 inch washer up against the nut. The barrel on the left of the nut measures .395 inch and is the part that screws into the Zinger hub about 10 turns. It is necessary to ream the front hole to 1/2 inch(on the hub). I can tighten it up enough to be safe and no slippage. I flew the Zinger 4 blade today and will post performance data soon. I also flew the Varioprop with the pitch set at 20 inches and if the prop speed chart is to be believed it may have reach 125mph on one pass. ESC data on the Varioprop is consistent with previous flts. Amp draw is higher Rpm is still too high and ESC temp is up too. I am going to back off on the pitch to 19 inches for the next flight. The Zinger 4 blade is way up on current draw- watts were 7000 and flight speed around 80mph. I also think it almost drained my flight pack. It might work better with 20-16 blades and this motor.