Official NYPD Knit Cap. A winter knit hat is now authorized as an optional uniform item for all uniformed members of the service, a NYPD department memo read. The department is allowing rank-and-file officers to wear knit hats instead of their traditional headgear. The approved optional winter knit hat must be navy blue in color with ‘NYPD' embroidered on the front in white one inch block lettering,”