A4 Self Seal Invitation Envelopes, 4 1/4″ x 6 1/4″, Avocado Green, 50/Pack (4872-27-50) | JAM Paper Cheap

Specifies the primary material of the envelope (e.g. paper, plastic, kraft, vinyl, Tyvek, high-density polyethylene, etc.). Tyvek, unlike standard high-density polyethylene (HDPE), is a synthetic material made from HDPE fibers and manufactured solely by DuPont.

Paper weight, stated in pounds (lbs.), is calculated by weighing a ream (500 sheets) of the basis size (master uncut size) of that paper type. For example, the basis size of bond paper is 17″ x 22″ with a ream weighing 20lbs; the basis size of watercolor paper is 22″ x 30″ with a ream weighing 140 lbs.