I’ve started using GWS Rubber Propeller Adapters as a wheel collar since they seem to do a good job of keeping wheels on the landing gear, are relatively light, and are easy to install. I had no idea what the part was when it arrived with my Slow Stick kit, and it was only later that I saw what they were mainly used for. I figured they had something to do with a propeller since they were stock in the propeller area at Aero Micro. One requirement of using the propeller adapters as a wheel collar is that it’s easier with a wheel with a thinner hub since the adapters are a little bit thicker than a normal wheel collar.