At Alpine Bathtub Liners & Plumbing, each liner is custom made, so it is the perfect fit to your tub. They are made of high quality acrylic. They are not porous, which makes them very durable, and extremely easy to maintain. Without a liner, the only way to update your walk-in bathtub would be to remove your old tub and replace it. Removing the tub means disassembling your whole bathroom. Using a liner gives you all of the benefits of a brand new tub, without the hassle of tearing apart your bathroom.