The Trevi 21BAKEHWJS 21' x 54" Round Bayview Key Above Ground Full Print Unibead Vinyl Pool Liner uses UV-resistant vinyl to reduce sun damage and provide superior performance, year after year. All Trevi vinyl liners are computer-designed and manufactured by the brand to exacting standards, ensuring a precise fit. In addition, they use the very latest assembly technology, which sets their products apart from the competition.