Cool! Ive been waiting for someone on tower to release a quality 5mm pinion. I hate the Century pinions because their just steel and they wear so fast. Im sure they would work fine meshing with a plastic/nylong spur but thats not what us here on RCM are about. Its all about steel/aluminum/alloy... Gotta have the best of the best and I think RR has finally delivered what Ive been waiting for.