From what I understand it's brass, so it's a soft material. However, after several adjustments trying to set the pressure, the screw stripped the brass threads. You should get the correct torque as there is another vent on the opposite screw size under the black cover. How tight you tighten the screw can affect the pressure in the regulator block. Like I said, it's very picky. I would recommend either buying a solid pressure model or looking for something else.
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