What I have is 18 inch rotors that are 3/8 thick that we're mounted in a traditional wheel hub then upgraded to a solid shaft design . The center hub is 1/1/2 keyed could be changed back easily . The magnets are expoxy down with a set pin on the end to prevent magnets from ever taking off . I have had these plates for over a year with no problems . I am upgrading to 23 inch rotor plates with bigger magnets . I thought 250.00 would be a good price magnets alone now are 9.99 a piece . Buyer pays freight , I will try to update with photos or just check my topic in wind ( direct drive on a solid shaft). Questions email at jarrodcramcram@ yahoo.com