Set up your piece item as you would any other with the exception of the following:

 

1.The Unit of Measure field must be set to PC. (Be sure to include the period at the end)
2.The Pieces per Case field must be set to the number of pieces in the master case item.
3.The Case Item Number must be set to the Item Number of the master case item.
4.The Piece Item Number field must be left blank (no value).

 

 

 

The example above illustrates the CASE item on the left and the PC. item on the right.