Our Classic Series in-ground winter pool covers are constructed of heavy-duty polyethylene material with extra material that extends beyond the pool size. This additional material helps ensure complete coverage allowing extra room for water tubes. Edges are either self edged with double chain stitching or reinforced with a stitched on 2” binding preventing wear and tear. The covers’ topside has been treated to inhibit damaging ultra-violet rays and the bottom sides have been treated to prevent the growth of algae.