Blake Envelopes. Paper Weight: . Dimensions: 106 (W) x 229 (H) mm. Colour: Cream. Gummed flap for a long shelf life and reliable sealing High quality 80 gsm paper Suitable for brochures, catalogues etc. Low Window Window 32 x 114 mm, 18 up, 32 left Catering for all sizes in wallet, pocket, gummed and self-seal envelopes. A range of paper grades available, all with excellent environmental credentials.