Genius Pipe Evolution SliderGenius Pipe Evolution Slider is a welcome upgrade to the Classic Genius slider with easier packing, increased bowl size and improved airflow. When you slide the round opening of the Genius Evolution Slider over the bowl, the thickness of the slide adds more depth. Switch between the small and large opening based on the extent to which you'd like to burn the contents of the Genius Pipe bowl. You don't need to remove the entire Genius Evolution Slider to check if the bowl is spent. Just slide it to the large round opening to inspect the bowl. Genius Evolution Slider follows the 4th rule of Zen design, melding function with aesthetic with an intense focus on the essential.