A while back I bought a Dubro True-Spin propeller balancer. A very sensitive, precision instrument when levelled properly. Unfortunately, the shaft supplied by Dubro is designed to work with propellers that have a hole through the middle. I put a bit of pink fuel pipe over the end of the shaft and this allowed me to “sort of” screw on CW and CCW props and then “sort of” balance them, but I never felt that I was getting entirely accurate results. I was browsing through another RC forum when I came across Muscleflex's prop balancer shaft. This has been purpose built to work with the Dubro balancer and DJI self-tightening props. It has the CW thread at one end and the CCW end at the other, and one end is coloured black to show that it is for the props with the black nut (CCW). It has been beautifully machined from aluminium rod, and I have to say that it works very well indeed. I have had it about a week now and I have used it to re-balance all my props very accurately. I am now going to get my local machinist to make me some threaded collars for each end so that I can screw my Phantom's motor bells in and balance them as well. Balanced props and motors mean : 1. The engines use less power, so you get more flight time 2. There is less engine wear 3. You can shoot cleaner video because there is less vibration through the airframe I can thoroughly recommend these rods and anybody who wants one should do what I did and email email@example.com He will email you back and tell you how to go about getting one. They are not expensive and he is a jolly nice chap. I got mine in 3 days.