ERF6000 : Indexbal endmill with 20mm high posi-rake button insert for difficult-to-cut material
  DesignationStockDCAPMXCICTDCXDCONMSLSLFGICATGIREMgiic
  ERF6050R Available50.0010.00370.0032.00080.0120.006804360 0
  ERF6063R Available63.0010.00483.0032.00080.0120.006804361 0

These are not irregular pitch spec.