These envelopes were used for an engagement party invitation the size and dimensions were the perfect fit so they worked out well; white was a good color match as the invitations was simple and not with a lot of color and we wanted all the guests to have the same not different colors. If these envelopes were for wedding invitations we would probably pick a colored envelope so they would match the colors for the wedding party. This size will probably be the size that we use for the wedding invitation envelopes.
Just fold a piece of 8.5 x 11 paper in two and it fits perfectly in this envelope which is an attention getter especially if you use stickers and labels to distinguish each piece.