BOULDER SWIRL ABOVE-GROUND OVERLAP-STYLE POOL LINERS Our premium liners are constructed of heavy gauge vinyl and will maintain their beautiful appearance for years. Strong, double-welded seams help our liners withstand winter’s worst. Overlap liners are backed by a 25-Year Warranty on heavy gauge. Flat-bottom overlap liners will fit either a 48” or 52” sidewall. Available in many colors and styles.