This has been much copied, so I don't know about the knock-offs, but I've had some of these for more than ten years and just bought some that are smaller and larger for different jobs. Great for showers, counters and I keep them in the cars as well. Easy to maintain: when dirty toss them in the washer. Just remember to not put them in the dryer. Keep them damp in the tube and they're always ready. If they dry out, just soak in warm water.