METAL STEM & Screw thro bowl
US patent 2,250,643 29 July 1941 inventor Frank N Mariani, New York
The insert at front of pipe acts as a valve to control smoke flow, push fit into stem. The bowls are known with slot headed screw through base of bowl, and also an integral screw attached to bowl
At present unsure of actual manufacturer.
Overall length 5 1/4 inch (134 m/m)