The ripple foam helps to protect hackles on larger dry flies while the flat foam will hold small and large flies alike. Molded from a high density plastic with a metal hinge pin, and positive snap closure, thsee 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. 5-5/8" x 3-3/4" x 1-5/8"