This a fully enclosed infant one piece seat with a high back to offer extra support for smaller children. Made of 70 duro EPDM rubber with an insert and heavy duty rust resistant triangular hardware. EPDM: Ethylene-propylene-diene-monomer which is a synthetic rubber material which helps prevent crazing, cracking and oxidizing. This swing has a smaller leg opening to ASTM F2373 for children 6 to 23 months. Leg holes 4.25" in diameter. The seat should last 2 years in harsh conditions and up to 5 years in optimal conditions. Some conditions may require replacement sooner.