18.3″L x 14.1″W. NO SLAMMING: Seat closes slowly and quietly with a tap to eliminate pinched fingers. INSTALLS WITH A SNAP: The STA-TITE Seat Fastening System is easy to install with just a wrench. SOLID PLASTIC: resilient plastic with molded-in color which resists chips, wear and stains. FITS MOST ELONGATED TOILETS: Including Kohler, American Standard, TOTO and many more.