WMy son and I bought one of these each to use in our Tamiay mini M05 cars. First time we used them they lasted less than one race shredding all the teeth off the gears almost immediately. A terrible product obviously made from inferior plastic. Anyone thinking of buying one of these should back away quickly, they are just not worth anything. I asked at our local club about these and wish I had before I bought them as everyone I spoke to had the same opinion, that the gears were terrible quality and did not last. Be warned!