Burners according to DIN 30665 cannot be switched off completely. A small flame remains burning even if needle valve or stop cock are turned off. The gas flow shall be disconnected by means of the central stop cock in the laboratory.
POA means "Price On Application". Items displaying POA instead of the sell price do so for a number of reasons, not least because we anticipate some additional information is required in order to supply the most suitable options/configuration to each individual customer.