Any pen can be used for drawing.

Pens with a diameter between 9.6 mm and 11.4 mm can be inserted into the holder.

When using a pen smaller than 9.6 mm, wrap masking tape, for example,around the areas marked 1 and 2 in the illustration below so that the pen will be thick enough to fit in the pen holder.

Adjust the thickness and position of the tape wrapped around the pen according to the actual-size illustration on the packaging and in the manual included with the universal pen holder.