This signature boxes is perfect for most flies. Dry flies up to size-4 fit easily. Two boxes snapped together will fit many of the medium size pockets on vests. Each box measures 5-3/4" x 3-7/8". Molded from a high-density plastic with a metal hinge pin and a positive snap closure, the boxes are lightweight and will last for years. Interlocking feet molded onto the bottom allow the boxes to be connected to one another. To protect against loss, a lanyard loop attachment is incorporated into each box.