Machined 6061 case, 1/2 steel shaft, 1/4" thick NdFeB magnets and a 4-pole armature! To top it all off, 82% efficiency! I love these things!
I used one back in HS in a Battlebot my shop class built. It spun up a 24 pound steel bar to 2000 RpM (3:1 chain drive) in about a second.
