Pool liners cushion the sides and bottom of pools with a smooth vinyl layer. With pool liners the general rule of thumb is the thicker the liner - the longer it will last and the more comfort it will provide. Pool liners can be smooth vinyl or have a beaded or ribbed texture. They generally come in thicknesses of 20 to 30 millimeters, and in every color and pattern imaginable to accent your pool's deck and rim. If you can't find a liner to fit your pool, you can order a custom-made pool liner online. Many manufacturers try to sell pool liners that are a mix of different plastics; however, a pure vinyl pool liner is the most durable choice. Depending on the shape and size of your pool, inground liners range from $700 to $1,500, while above ground liners range from $100 to $500 online.