An optical disc has a first transparent substrate, a second substrate, and at least a first and a second recording layer formed between the substrates. Each of the plurality of reamer cutters may be replaceable by removing at least one of the plurality of ball and socket connectors from the reamer body. Such improvement in magnetic characteristics decreases deviation in switching characteristics in arrays of such magnetoresistive devices such as those present in MRAMs. In another form, the disks are axially spaced apart flat plates of progressively greater diameter extending from drive shafting at the axis of rotation. The conveyor belt includes a first region that is to receive the part of the recording medium and a second region adjacent to the first region.