A smart choice to insulate your pool, the Round Overlap Pool Liner uses sunlight to warm the water while minimizing heat loss. This premium vinyl pool liner, sunlight, is constructed of heavy-gauge vinyl to last longer and maintain its appealing appearance for years. The unique Lamiclear process provides maximum protection from pool chemicals and the sun's damaging UV rays while its strong, double-welded seams will withstand winter conditions. The 21' pool liner also has overlap liners that will fit either a 48 inch or 52 inch sidewall. This Round Overlap Pool Liner is a good way to protect your pool.