GPC Winter Covers 112442IGB 18' x 36' Rectangle Inground Pool Winter Cover. This item is intended for use during the winter offseason. The heavier woven polyethylene scrim and coating makes this cover strong and able to withstand wind, sleet and snow. The cover should be able to comfortably float on the pool water without excessive stress. Covers are sewn with commercial grade thread for maximum strength with no rust aluminum grommets.