Leaders and tippets are generally constructed of monofilament or fluorocarbon fishing line. The surface is composed of monofilament polyethylene blend fibers tufted into a polypropylene backing. Prolene is a synthetic, monofilament, nonabsorbable polypropylene suture. PVDF is used for specialty monofilament fishing lines, sold as fluorocarbon replacements for nylon monofilament. Continuous reinforcement uses monofilament wires or fibers such as carbon fiber or silicon carbide. The rectus fascia is closed with monofilament absorbable suture. Fluorocarbon is also a denser material, and therefore, is not nearly as buoyant as monofilament. The fabric can be silk, nylon monofilament, multifilament polyester, or even stainless steel. Olefin fibers can be multi- or monofilament and staple, tow, or film yarns. Typical line is 20 pound test monofilament or 30-60 pound test braided line. A short length of monofilament plastic/nylon string hangs down from the cervix into the vagina. Short monofilament plastic/nylon strings hang down from the uterus into the vagina. Lippes also devised the addition of the monofilament nylon string, which facilitates IUD removal. This is usually made from string, wire, mesh, monofilament line or epoxy. The most common type is monofilament made of a single strand.