What is the difference between the Sleek and the Streamline models?

The main difference between the Streamline and the Sleek model is due to the small indentation near the cap of the pens. Our Streamline model has a completely smooth surface when the cap is unscrewed. When capped, a small step appears between the cap and the barrel. Our Sleek model, however, has a completely smooth surface with the cap screwed on.

When the cap is unscrewed, a small step appears between the barrel and the section.