This tool is used to set the correct settings of the 2nd stage  ATX-MTX-AT series regulators.

A tube shape tool with different sizes undercuts at each end.

One is smaller NO GAS FLOW – identified as “breathing gas is not flowing” and the other is larger GAS FLOW – identified as “breathing gas is flowing”.

During the second stage adjustment, the objective is to precisely position the orifice ( AP2033 part)