The #11 Open End (4 1/2 x 10 3/8) in 28lb Bright White is a standard sized business grade envelope. It features a flap on the short side of the envelope, which is sealed by a moistenable strip, to secure the contents inside. This Open End envelope is ideal for office use as well as for home or school. The 28lb. Bright White sock provides protection and privacy of its contents and is constructed with a center seam. Available both plain and printed for customization, branding and creative uses, starting in small quantities of 50 to large quantities of 50,000 and more.