The COPING24 Above Ground Overlap Coping Strips will help ensure a firm, proper liner installation. These plastic, non-corrosive, 24" long clips hold your liner in place on the pool wall before re-installing the top rail.Coping Strips by Pool Size:15' Round - 23 Strips18' Round - 28 Strips21' Round - 33 Strips24' Round - 38 Strips.