The reversible, woven polyethylene ones work great for us. Water goes through, they dry very fast, and fold up nice and flat. Most the places we go have crushed gravel or sand sites, and the mat helps keeping the white dust and dirt on the ground instead of tracked into the trailer. Also helps keeping newly mowed grass from getting tracked all over. If the site has a nice slab or patio, there really is no need for the mat. We also have two small mats for each door - one at the bottom of the steps, and one right inside the door - to wipe your feet on. Unfortunately, the dogs don't always wipe their feet as well as we would like them to .....