These are the wheels we use on our own standard builds they're made out of high quality 60 series Aluminum CNC machined in England on state of the art machines for accuracy, balance & concentricity. 
 
Included are -
 
2 X 50mm platen wheels supplied with bearing & spacers.
1 x 75mm crowned tracking wheel supplied with bearings & spacers.
1 x 130mm crowned drive wheel supplied with bearings & spacers.