A brass threaded needle valve and a rubber O ring for gas regulation, and air vents for air regulation.  With flame retainer at top.
With one piece die-cast heavy base and riffled nozzle and adjustable gas and air inlets.   

Chemistry School Lab Equipment Suppliers in India 

Ltekonline are the manufacturers of Adjustable Bunsen Burner Lab used to demonstrate engineering principles in Engineering Colleges, Engineering Schools and Chemistry Lab Equipment for Engineering Teaching Lab in Universities