Raised bed liners keep soil contained so you can install the beds on a patio, paved area or concrete slab — any hard surface — without soil washing out and making a mess. They help prevent weeds from infiltrating beds set in the lawn, too. Polypropylene fabric allows water to drain. Four sizes: 3' x 3', 3' x 6', 4' x 4' and 4' x 8'. The 3' liners are 10" high, perfect for Grow Beds (fold the sides down for lower beds). The 4' liners are 6-3/4" high and may be used in beds of any depth.