These heavy-duty glass cleaners consist of a 3” x 4” x 1” yellow sponge backed with crushed walnut shell.  Crushed walnut shell scrubbers are the best performers for removing heavy algae on glass aquariums.  Furthermore walnut shell is non-abrasive on glass.  They are offered three separate ways: Glass cleaner pad only (12050); glass cleaner pad on a 15” stick (12060); and glass cleaner pad on a 15” stick with a scraper (12070).