These blenders have more slits on the bottom to increase airflow. There is essentially zero resistance. These pair amazingly with low resistance pieces, such as the RBR. Works best with a pillar; size 5-6mm diameter and 15-30mm length
Tall tube 
18mm diameter 
3mm thick wall 
Thick dish 
Fully worked joint 
Beveled top edge 
Maria joint 
Premium ground joint 
Flame polished etched dish