Plackets are almost always made of more than one layer of fabric with interfacing between the fabric layers to give support and strength to the fabric area. The placket not only is a style statement, but is also functional, as if it is sewn well, it lessens the stress on the button area of the shirt when the garment is worn. The placket may overlap to make the shirt more tactile friendly–keeping fasteners from rubbing against the skin and even hiding undergarments. Of the style choices, the plain front gives a simple streamlined look, a front placket adds dimension to the shirt, and a fly front gives the most formal result.
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