Newly designed, we have removed the grommets and the washers are welded to the insert that is molded into the seat. The insert is covered with EPDM material that withstands harsh weather and fading. EPDM: Ethylene-propylene-diene-monomer which is a synthetic rubber material which helps prevent crazing, cracking and oxidizing. Seat size is 6" x 25" x 3/8" thick. The seat should last 2 years in harsh conditions and up to 5 years in optimal conditions. Some conditions may require replacement sooner.