NYFASHION101 Wavy Wide Brim Veil & Feather Kentucky Derby Sinamay Hat One size fits most for this wide wavy brim Kentucky Derby dress hat. Fully measured: 20" x 20", Height: 5" Material: 100% Sinamay. Adjustable drawstring within the hat to secure a tight fit from any breezy day. Veil and feathers with floral accent for the attention grabbing moment! Great for Sunday brunches, picnics, or the seat at the Kentucky Derby!