Check the listing for details. SEACHEM ALGAE SCRAPER REPLACEMENT BLADE REFILLS - 3 per PACK for AQUARIUMS x2. Condition: New. Listed at 17.99 USD. SEACHEM Listing is for ( 2 ) : SEACHEM ALGAE SCRAPER REPLACEMENT BLADE REFILLS 3 per PACK Compatible with all Seachem Algae ScrapersMetal easily removes tough algae in glass aquariums.Choose from two blade positions/heightsSafely hide blade when not in useNot for use on acrylic aquariums Product Description: These algae Scraper blades are compatible with all Sachem algae scrapers. Install the blade by snapping open the scraper cartridge (using the divot found on both sides of the cartridge), placing the blade and easily snapping it back together. The cartridge easily slides out of the Scraper, is able to be positioned in two different heights as well as a third position that hides the blade safely away when not in use. These metal blades will remove tough algae with ease and come with three in a pack. Although these scrapers are a necessity for any aquarium, the blades should not be used on acrylic tanks as they may scratch them. # 3212 Please feel free to contact me for International and combined auction shipping rates or with any questions or concerns that you may have about my products. Thank you !