The sun visor on the Coupes and Tudor Sedan were covered with top fabric. They just tuck up into the header cap and are fastened on the sides with the screws. The top material acts as an anti squeak/anti rattle for the visor.
The 1930/31 cars have a welt strip on the front header cap but they are set up differently from the older models. The 1928/29 already have the steel cross support above the windshield so they didn't need a cap.