Drop handlebars are characterized by their curved shape, which allows the rider to adopt an aerodynamic riding position. They typically have a central section with a cylindrical shape for gripping and two curved extensions that extend downward and outward. This design offers multiple hand positions, allowing the rider to vary their posture for comfort and control, whether they're riding on flat terrain, climbing hills, or descending.
If you have a specific product or design in mind that you're referring to as "2 piece drop down handlebars," please provide more details or clarify your question so I can offer a more accurate explanation.