I have used the typical beret style with a ribbed stitch pattern, thick stranded yarn. The visor keeps its shape without a stiff cardboard inlay, but allows some reshaping.
The crown is roomy enough to tuck in a bit of hair or a bun, small dreads or low volume long hair, but is not as slouchy as most of my other (dread) tams.
Width at brim 20", stretches to 25"
Length from crown to rim (WITHOUT FRONT VISOR) 8"
Diameter of crown across 10,5"
I suggest hand washing and flat drying, care suggestions come in your package.