To Edit a Custom Units System To redefine a units system that you previously created, In Part or Assembly mode, click Edit > Set Up. The PART SETUP or ASSEM SETUP menu appears. Click Units. The Units Manager dialog box opens to the Systems of Units tab. Double-click the custom units system you want to edit, or select the system and then click Edit. The System of Units Definition dialog box opens. Redefine the units system as necessary, and then click OK to close the dialog box. Click Close to close the Units Manager dialog box. See Also About Measurement Units About Modifying Measurement Units Tip: Rules for Modifying Units