Robelle 4718-4 Rip-Shield Olympus For Round Above Ground Swimming Pools, 18-Ft Round PoolThe Robelle Olympus Winter Pool cover is an extra heavy-duty solid winter pool cover Solid pool covers do not allow water to pass through their material The Robelle Olympus Winter Pool cover features an extra heavy-duty 13 x 11 scrim The extra heavy-duty polyet..