Radiant Pools 4077-21 Deluxe Winter Cover for 21' Metric Round Above Ground Pool - This winter cover is designed exclusively to fit into both the 2" standard and 4" premium coping of Radiant Metric Series Pools! The custom fit provides perfect coverage for winterizing your 21' Radiant Metric round above ground pool. Made from tough triple laminated no-rip polyethylene fabric and triple edge reinforced perimeter, this swimming pool winter cover is 30% lighter than other winter covers, yet is 40% stronger than any other swimming pool winter cover! This cover is available for different pool sizes.