A sloped front metal cabinet that measures 5 7/8"W x 4 1/8"D, 1 3/8" front height and 2 7/8" rear height, containing 1-35 ohm rheostat and knob plus 2-1/4" phone jacks. Power source is 5 foot cord with 1/4" phone plug which will plug into all National power boxes or to National battery hookup (B13). You can also adapt it to fit other power boxes. The purpose of the Auxiliary Rheostat box is to slow down machines when the power from the power box is considered too strong for your technique of tattooing, or to add a control where none exists, such as battery hook ups.