Why won't this 3/8 male connector for a natural gas dryer fit a 3/8 female connector? - Home Improvement Stack Exchange

My gas pipe is 3/4' and I need a gas valve and to connect it to a

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Why won't this 3/8 male connector for a natural gas dryer fit a 3

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natural gas - Dryer Fittings, Was NG, now LP, but Fitting on Back

3/8 FPT Natural Gas Female QD Fitting : Patio, Lawn

Why won't this 3/8 male connector for a natural gas dryer fit a 3

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