Half Scale - 9mm Regular Curve - Fixed Tip Pen. With each depression, the #21 tip forms two halves of a raised scale. This design allows for slight variation in scale size.
#21 tips in sizes up to and including 8mm Regular curve, 8mm Flat curve, and 6mm Deep curve have a steel blade welded onto the tip. Larger tips are formed completely from tip wire as shown above. They are not as strong as the smaller steel-blade tips. Uniform scales are easily achieved too.