Excellent material for capturing large particulate matter for the mechanical portion of the filtration process. The sleeve makes putting it on real easy. It can be used more than once. Just wash it out well when gunk builds up -Although, I wouldn't recommend doing it more than once as it gets stretched out. I change it out once a month and I think that gets the best results. It keeps my water pretty clean and is worth the money. Its 20inches long so will work with both the 16 & 20 high System II Aquariums.