ALG PIRANHA FLOATING MAGNETS Enables vigorous algae scrubbing without worry of detachment and having to dig the cleaner off the b Strong, impenetrable injected molded durable ABS plastic inner magnetic housing is fresh and saltwat When substrate, gravel etc. get caught in the cleaning pad of aquarium algae cleaning magnets (which Lighter inner cleaning assembly makes for a stronger magnetic attraction, better cleaning ability an No more strings to get tangled.UL&gt;Qualities of our floating aquarium algae magnets: &lt;UL