ALIENTAC Aluminum 1:10 12mm Wheel Hex Adapter Hexagon Combiner Wheel Hub Black for RC Crawler SCX10 4PCs

They look really nice but the tightening allen screws strip easily and were not able to tighten these adapters onto a 4 mm shaft. I tried using them for a Dagu Rover 5 tracked robotic platform (which has 4 mm shafts) to replace the treads with regular RC wheels. Note that these MIGHT work perfectly fine if you have an actual RC car/truck (which is why I give 3 stars instead of 1) but my guess is that the center hole is bigger than the 4 mm listed in the description. For my application I was able to use a different type of brass adapter with setscrews rather than these clamp-on type.