Velpine® (White Kraft) Open Side Booklet with Showcase Window Open Side Booklets have their opening on the long dimension - offering inserting ease and convenience. These envelopes are manufactured with durable, SFI Certified white kraft paper, a large "showcase" poly window, two side seams under construction and a traditional remoistening seal.White Kraft (SFI CERTIFIED) 84% Brightness Vellum FinishTwo Side Seams Under Poly Window Remoistening Seal Flap Down